What is Chemistry? It is the study of the basic units that make up all substances. These basic units are called atoms. There are some substances that require two or more atoms to exist, and these combinations are called molecules. The atom or the molecule is the smallest unit into which any substance can be broken. These basic units of atoms and molecules can react with each other to form new substances with completely new characteristics.

The world is made up of two basic chemical systems--organic and inorganic. The easiest to understand is inorganic, but many of the basic principles apply also to the organic system.

You, no doubt, already know that inorganic chemistry is concerned with non-living substances while organic chemistry deals with substances which have their origin in a living plant or an animal body.

The inorganic world is made up primarily of salts and oxides. The rocks, sand and minerals of the earth are made up of these. Coal, on the other hand, is an organic substance because it has its origin from ancient decayed plant-life.

Every salt and oxide can be separated into the components from which it is made. Oxides are atoms which unite with the oxygen atoms of the air to form this new substance. Sand is silicon oxide (called silicon dioxide because it reacts with two oxygen atoms - (SiO2).

Salt can be separated into two components--an acid and a base. The acid and the base are opposed to each other and react actively when mixed together to form this salt. The most common example is table salt, iviiicii can be formed by reacting hydrochloric acid with the base, sodium hydroxide. The chemist writes this in symbols as follows:

              Hcl       +         NaOH         -       Na Cl        +      HOH (H₂O)

(Hydrochloric acid) + (sodium hydroxide) (sodium chloride) + (water)

TITRATION AND pH

In our first lesson we learned that acids and bases react together in a reaction we call neutralization. This is the reaction we are applying when we use our titration kit.

By using a set sample size we can determine the concentration of that sample if we accurately measure the amount of titrating (neutralizing) solution required to neutralize the sample. The drops of a titrating solution are a good measure because drops are relatively consistent in size. If the product is alkaline (base) we use an acid; if the product is acid we use a base titrating solution. Alkaline, for example, requires an acid titrating solution while the acid require an alkaline titrating solution. In order to see when the point of neutralization has been reached, an internal indicator is used. The indicators are organic substances which change color at a particular pH.

The pH of a solution reflects the intensity of an acid or a base. The pH scale runs from 0 to 14. The neutral point is 7. Any pH below 7 is acid and pH above 7 is alkaline. The closer the acid pH is to "O", the more intense is the acid. The closer the alkali (base) pH is to 14, the more intense is the base.

pH SCALE     0 1 2 3         4 5 6       7    8 9 10      11 12 13 14
                        STRONG     WEAK    N   WEAK     STRONG
                        ACID             ACID     E    BASE       BASE
                                                             U
                                                             T
                                                             R
                                                             A
                                                              L

The pH is a measure of the intensity of the acid or the base and cannot be used as a measure of the amount or concentration of an acid or a base. The reason pH cannot be used as a measure of concentration is that it is a "logarithmic function". Don't let this phrase throw you, because all it means is that each unit of change is ten times the previous unit. For example, if it takes one pint of a given acid to bring neutral water to a pH of 6, it will take ten pints of the same acid to bring the solution to a pH of 5. You can see that the most rapid pH change occurs near 7.

Different acids and bases have different strengths and consequently different pH's for the same concentration. In other words, there are weak and strong acids and bases. Vinegar (acetic acid) is a weak acid and muriatic acid (hydrochloric acid) is a strong acid. Bicarbonate of soda is a weak base and caustic soda is a strong base.

Earlier we talked about internal pH indicators which are added into the sample. The most common ones we use are phenolphthalein and brom phenol blue. Phenolphthalein changes from colorless in acid to pink in alkaline solutions at a pH of 8.3. While the change is not exactly at 7, the change in pH is so rapid at this range that we can use it. The vivid color change makes it the most widely used indicator.

Brom phenol blue changes from yellow in strong acid to blue at a pH of 4. This gives us a good indicator for determining strong acid, usually referred to as the active acid content. When measuring an alkaline solution by titration, this point (brom phenol blue) measures total alkalinity.

                                                         _{º                           °}
H–O             +          H–O —>     H–O–H     +      H–O
     ½                                |                    |
     H                               H                  H
                              Hydronium                          Hydroxide
                                Ion                                          Ion

Definition of pH

Just as the kilometer is a measure of distance, and the hour a measure of time, the pH unit measures the degree of acidity or basicity of a solution.

To be more exact, pH is the measurement of the hydrogen ion concentration, [H⁺]. Every aqueous solution can be measured to determine its pH value. This value ranges from 0 to 14 pH. Values below 7 pH exhibit acidic properties, and values above 7 pH exhibit basic (also known as caustic or alkaline) properties. Since 7 pH is the center of the measurement scale, it is neither acidic nor basic and is, therefore, called "neutral."

pH is defined as the negative logarithm of the hydrogen ion concentration. This definition of pH was introduced in 1909 by the Danish biochemist, Soren Peter Lauritz Sorensen. It is expressed mathematically as:

                        pH= -log [H⁺]

            where: [H⁺] is hydrogen ion concentration in mol/L.

The pH value is an expression of the ratio of [H⁺] to [OH^-] (hydroxide ion concentration). Hence, if the [H⁺] is greater than [OH^-], the solution is acidic. Conversely, if the [OH^-] is greater than the [H⁺], the solution is basic. At 7 pH, the ratio of [H⁺] to [OH^-] is equal and, therefore, the solution is neutral. As shown in the equation below, pH is a logarithmic function. A change of one pH unit represents a 10-fold change in concentration of hydrogen ion.

In a neutral solution, the [H⁺] = 1 x 10^-7 mol/L. This represents a pH of 7.

                    pH = -log (1 x 10^-7)
                          = -(log 1 + log 10^-7)
                          = -(0.0 + (-7))
                          = 7.0

Since the concentration of hydrogen ions and hydroxide ions are constant in a stable solution, either one can be quantified if the value of the other is known. Therefore, when determining the pH of a solution, (even though the hydrogen ion concentration is being measured), the hydroxide ion concentration can be calculated:

    [H⁺][OH^-] = 10^-14

pH Values and Hydrogen/Hydroxide Concentrations

In Figure 3, the pH value corresponds to the number of decimal places under the column for "hydrogen ion concentration." The pH of the solution equals the exponential form of the [H⁺], with the minus sign changed to a plus. It is much easier to write or say "10 pH" than it is to communicate "a hydrogen-ion concentration of 0.0000000001mol/L."

                         [OH^-] concentration                         [H⁺] concentration
                                 (mol/L)                      pH                      (mol/L)

    FIGURE 3 Table of Relative [OH^-] and [H⁺] Mol/Liter Concentrations

How Is pH Measured?

The measurement of pH in an aqueous solution can be made in a variety of ways. The most common way involves the use of a pH sensitive glass electrode, a reference electrode and a pH meter. Alternative methods for determining the pH of a solution are:

Indicators: Indicators are materials that are specifically designed to change color when exposed to different pH values. The color of a wetted sample paper is matched to a color on a color chart to infer a pH value. pH paper is available for narrow pH ranges (for example, 3.0 to 5.5 pH, 4.5 to 7.5 pH and 6.0 to 8.0 pH), and fairly wide pH ranges of 1.0 to I 1.0 pH.

NOTE: pH paper is typically used for preliminary and small volume measuring. It cannot be used for continuous monitoring of a process. Though pH paper is fairly inexpensive, it can be attacked by process solutions which may interfere with the color change.

Colorimeter: This device uses a vial filled with an appropriate volume of sample, to which a reagent is added. As the reagent is added, a color change takes place. The color of this solution is then compared to a color wheel or spectral standard to interpolate the pH value.

The colorimeter can be used for grab sample measuring, but not continuous on-line measuring. It is typically used to determine the pH value of water in swimming pools, spas, cooling towers, and boilers, as well as lake and river waters.

A pH meter is always recommended for precise and continuous measuring. Most laboratories use a pH meter connected to a strip chart recorder or some other data acquisition device so that the reading can be recorded or stored electronically over a user-defined range.

Activity versus Concentration

Glass electrodes are sensitive to the hydrogen ion activity in a solution. Consequently, the concentration of hydrogen ion is not the only factor influencing the pH of a solution. The concentration of other chemicals in the solution, or the ionic strength of the solution, is also a major influence in the measurement of pH.

The term "ionic strength" is used to describe the amount of ionic species in a solution, as well as the magnitude of charge on those species. Examples of ion species compounds are sodium (Na⁺)sulfate (SO₄^2-), Calcium
(Ca²⁺) chloride(CI^-), and potassium (K⁺) nitrate (NO₃^-). The presence of these ions in solution tend to limit the mobility of the hydrogen ion, thereby decreasing the activity of H⁺.

The concept of limited mobility of the hydrogen ion is analogous to a person entering a shopping mall. If the shopping crowd is small, the person is free to move about the mall in any direction. However, if the mall is very crowded, the shopper has a difficult time moving from store to store which severely limits their activity. It is this same principle of a "crowded environment" that limits the activity of the hydrogen ion.

The following equation mathematically describes this effect on the activity of H⁺:

                pH = -log {[H⁺] x [ƒ]}
                where: ƒ is the activity coefficient

In solutions where the ionic strength is very low, the activity coefficient is 1.00 making the activity of hydrogen ion equal to its concentration. As the ionic strength of a solution increases, the activity coefficient decreases. This has the effect of lowering the activity of hydrogen ion which is seen as an increase in pH. The following example illustrates this point:

Example: The pH of a 0.00002 M solution of nitric acid can be calculated using this equation:

                pH = - log {[H⁺] x [ƒ]}
                pH = - log {[0.00002] x [ 1 ]}
                pH = 4.70

The value of [ƒ] can be derived from various equations, or found in tables published in:

CRC Handbook of Chemistry and Physics by Robert C West, Ph.D., Ed., CRC Press, Inc., Boca                   Raton, FL

Lange’s Handbook of Chemistry by John A. Dean, Ph.D., Ed., McGraw-Hill Book Company, NY, NY

The product of the activity coefficient and hydrogen ion concentration is equal to 0.00002. This means that the ionic strength of the solution has no effect on the pH calculation.

If the ionic strength were 0.1, the new pH can be calculated using this equation:

                pH = - log {[H⁺] x [ƒ]}
                pH = - log {[0.00002] x [ 0.75]}
                pH = 4.82

If the ionic strength of the solution were 0.1, the activity coefficient, [ƒ], would then be 0.75. The product of the activity coefficient and hydrogen ion concentration is now less than 0.00002. This causes the pH calculation of the nitric acid solution to increase by 0.12 pH unit. In this case, the ionic strength has a major influence on the pH of the solution.

The Nernst Equation

The general mathematical description of electrode behavior was described by the 19th century German chemist, Hermann Walther Nernst (1864-1941). He introduced the Nernst equation in 1889. It is expressed as:

                E = E_o-^2.3RTllog a_i
                        ^nf
            where:  E = total potential (in millivolts) between two electrodes
                            E_o = standard potential of the ion
                              R = universal gas constant (in Joules/mol-Kelvin)
                              T = absolute temperature (in Kelvin)
                              n = charge of the ion
                              F = Faraday constant (in Coulcombs/mol)
                              a_i = activity of the ion

The entire term "2.3RT/nF" is called the Nernst factor, or slope factor. This term provides the amount of change in total potential for every ten-fold change in ion concentration. For hydrogen ion activity, where n = 1, the Nernst factor is 59.16 mV for every ten-fold change in activity at 25°C. This means that for every pH unit change, the total potential will change 59.16 mV.

The following general equation may be stated for any temperature (since pH is defined as the negative logarithm of the hydrogen ion activity):

                E = E_o + (1.98 x ^10-4) T_K pH

However, the Nernst factor will change when temperature changes (T is not constant). At 25°C the slope of the PH electrode is 59.16 mV/pH unit. At 0°C the slope value is approximately 54 mV/pH, and at 100°C the slope value is approximately 74 mV/pH. The millivolt output of the glass pH electrode will change with temperature in accordance with the Nernst equation. As the temperature increases, so does the millivolt output. Specifically, the slope of the electrode is what changes.

The change in electrode output versus temperature is linear which can be compensated in the pH meter. The linear function for temperature vs. pH change can be expressed as:

                0.003 pH error/pH unit/C

If an uncompensated pH system were standardized in pH 7 buffer at 25°C, and then a sample at 23°C measured 4.00 pH, the error would be 0.018 pH unit (0.003 x 2°C x 3 units). For a measurement of 4.00 pH at 75°C (probably close to a typical worst case), an uncompensated pH system would read 4.45 pH.

The Standard Hydrogen Electrode

The glass measuring electrode has its electrochemical roots planted in the earlier use of the standard hydrogen electrode(SHE). The SHE is the universal reference for reporting relative half-cell potentials. It is a type of gas electrode and was widely used in early studies as a reference electrode, and as an indicator electrode for the determination of pH values. The SHE could be used as either an anode or cathode depending upon the nature of the half-cell it is used with.

The SHE consists of a platinum electrode immersed in a solution with a hydrogen ion concentration of 1.00M. The platinum electrode is made of a small square of platinum foil which is platinized (known as platinum black). Hydrogen gas, at a pressure of 1 atmosphere, is bubbled around the platinum electrode. The platinum black serves as a large surface area for the reaction to take place, and the stream of hydrogen keeps the solution saturated at the electrode site with respect to the gas.

It is interesting to note that even though the SHE is the universal reference standard, it exists only as a theoretical electrode which scientists use as the definition of an arbitrary reference electrode with a half-cell potential of 0.00 volts. (Because half-cell potentials cannot be measured, this is the perfect electrode to allow scientists to perform theoretical research calculations.) The reason this electrode cannot be manufactured is due to the fact that no solution can be prepared that yields a hydrogen ion activity of 1.00M.

Dehydration

Left out of solution, the pH glass membranes will become dehydrated. After this happens, the pH sensor will have slower response and a higher than normal impedance when it is put back into operation. Repeated dehydration and re-use will dramatically reduce the normal service life of the pH sensor. Prolonged dehydration will cause the glass membrane to completely fail.

If the reference electrode becomes dehydrated, it also will no longer operate properly. The electrolyte will leach out of the electrode cavity, through the junction(s), forming salt crystals on the junction surface. Over time, leaching will weaken the electrolyte potential, and may also cause a phenomenon known as a bridging effect. Both of these conditions will increase the output impedance, making the reference electrode output unstable. With continued dehydration, the impedance will rise to a level that become unusable to the pH meter.

Factors Detrimental to Electrode Life

A pH electrode operates similar to a hydrogen electrode within the range of

0.00 - 12.00 pH (where the alkali error affects the reading). This is also known as a sodium ion error. Within this range, the output slope of the electrode corresponds to the theoretical 59.16 mV as defined by the Nernst equation.

As with all glass, pH glass is susceptible to chemical attack. Temperature changes can alter the rate of this attack. For every 30°C rise in temperature, the rate of attack increases ten-fold. Accordingly, electrode life is shortened in process solutions, with elevated temperatures. Strong acids and, to a greater extent, strong alkaline solutions attack the glass membrane. Even neutral solutions that contain high concentrations of alkaline ions, sodium ions in particular, attack the glass. Using a pH sensor with a glass formulation that is inappropriate for the application may render the sensor inoperable after only a short time without any visible glass defects.

Hydrofluoric acid (HF) will readily poison the glass membrane when the pH is below 6.00. The greater the fluoride ion concentration, the faster the electrode will fail. The fluoride strips away the gel layer of the glass membrane rendering it inoperative.

A special electrode manufactured from antimony is available for measuring pH in solutions containing HF. The antimony electrodes exhibits similar properties to glass electrodes within certain limits. One drawback is that the repeatability and speed of response for an antimony electrode is inferior to that of a glass electrode. Also, antimony electrodes are only linear between 3.0 and 8.0 pH, and should only be specified when hydrofluoric acid dictate their use.

Transportation

Freezing, extreme heat, vibration, and mechanical shock must be avoided when transporting electrode, whether within a facility, or from one facility to another. Always try to reuse the original box and packing materials, if possible, to transport electrodes.

When shipping the electrode using motor freight, select a carrier that will guarantee that the package will not be exposed to extreme temperatures. usually sending the electrode by an overnight delivery service ensures that the package will not be exposed to the elements long enough to damage the electrode.

Storage

pH sensors (electrode pairs, combination electrodes, and differential styles) should be stored in ambient conditions between 10 and 30°C. Protective caps, as well as solution storage caps, should be kept intact and installed onto the end of the sensor, as provided by the manufacturer.

The best solution for storage purposes is a 3 to 3.5 M KCI solution. This solution provides a neutral-to-slightly acidic environment for the glass electrode, and will not impose a memory on the glass (much as Ni-Cad batteries can have memories imposed upon them when they are not fully discharged prior to recharging). Should KCI solution not be available, appropriate substitutes in order of preference are:

                    pH 4 buffer
                    distilled water
                    tap water

Under these conditions, the glass measuring and reference electrodes can have a shelf life of three to five years.

METAL CLEANING PART I - SOILS AND SURFACES

A basic guide for every metal finishing employee or salesperson. Metal cleaning is definitely an essential step in every metal fabricating, assembling and finishing operation. If you can start with a clean part the rest of your job can be a whole lot easier.

Cleaning is generally defined as the removal of dirt or soil which is simply matter out of place. Painting, plating, or porcelain enameling are finishing operations that require the metal surfaces to be free of industrial soil. What do we mean when we say industrial soils? Industrial soils can be defined as:

(1) Buffing compound residues
(2) Cutting oils
(3) Drawing compounds
(4) Heat scale
(5) Heat treating salts
(6) Paint, stop-off lacquers, inks
(7) Phosphate coatings, with and without oils
(8) Quenching oils
(9) Rust and corrosion inhibitors
(I 0) Slushing oils
(11) Smuts
(12) Tarnish and finger prints
(13) Inside and outside storage dirt
 

As you can readily see from the aforementioned list, soils encountered in metal finishing operations vary widely. They may be of an oil, grease, or wax nature such as a result from the use of metal forming lubricants and coolants, rust preventative compounds, buffing and polishing materials. These type s of soils respond to solvent and alkaline types of cleaners.

Pigments, abrasives, metal chips, smuts and shop dust are usually held to surfaces by oils or greases. Alkaline cleaners are used to emulsify the oily binders and disperse the solid particles.

Oils or organic finishes may be combined with oxide films, rust, heat scale, tarnish, finger prints, phosphate  coatings or chromate conversion coatings. When this happens, precleaning with solvents or alkaline             cleaners may be necessary prior to acidic cleaning for effective removal of these soils. Acid treatment may be undesirable at times; chelated alkaline cleaners (IF THEY ARE NOT A WASTE TREATMENT PROBLEM) should then be used to remove these soils.

Pre-planning in the choice of the various industrial metal working or finishing chemicals can minimize cleaning problems. Such as, the use of easy to remove buffing and drawing compounds well as cutting oils and precleaning before heat treat. These are just a few hints that make the old cliché pay off; "An ounce of prevention is worth a pound of cure."

Now that we have established what industrial dirt and soil is, we have to decide when to clean. Cleaning is generally carried out:

After: Stamping      and before: Painting
          Drawing                             Plating
          Buffing                                Phosphatizing
          Machining                          Inspection
          Polishing                           Assembly
          Heat treating                     Welding
          Storage

Cleanliness, like most things in life is relative. It is virtually impossible to obtain, within general industrial operating parameters, chemically clean surfaces - surfaces that are completely free of films. A more commonly acceptable definition of an industrial clean surface is, "one on which objectionable surface films have been replaced by films more suitable and acceptable for electroplating." We can simply extend this definition to include painting, phosphating, etc.

To date, no satisfactory method has yet been devised to absolutely ascertain the cleanliness a surface. There have been cases where fluorescent dyes and radioactive compounds have been used to test for soils. These are isolated and narrow attempts to check for cleanliness.

In industrial operations, the most practical test is the presence or absence of "Coates break" on the metal surface. If water rinses from the surface in one continual sheet the surface is considered clean; breaks in the sheet of water, or water beads on the surface are evidence that not clean.

Not all cleaning operations require the same degree of cleanliness. Parts being cleaned between manufacturing processes to permit inspection, etc., are protected from rusting and finger printing, if a light oily film remains after cleaning.

Surfaces to be bronzed, galvanized, tinned, soldered, spot welded, or finished with electroplated organic or porcelain enamel coating require a high degree of cleanliness to insure adhesion.

We now know what cleanliness is and have identified the roles of industrial soils and dirt. We are now ready to choose a cleaner, or are there other factors we have to consider before we select a cleaner? The following list of factors affecting the selection of a cleaner is a list you should be very familiar with. Use it as a check list before selecting a cleaner.

Parameters of Cleaners Selection
(1) Surface to be cleaned
(2) Soil to be removed
(3) Required degree of cleanliness
(4) Water quality
(5) Cost
(6) Safety
(7) Disposal
(8) Method of application

If you are somewhat familiar with the soils to be cleaned, how about the surfaces which are commonly cleaned? Listed alphabetically are some of the surfaces that are generally cleaned in industry:

Aluminum, brass, bronze, copper, galvanized metals, glass, iron, lead alloys, magnesium, monel metal, nickel, nickel silver, plastics, silver, steel, stainless steel, tin, titanium and zinc.

The ferrous or iron surfaces are by far the most prevalent cleaned surfaces in industry. The ferrous metals, titanium and magnesium alloys are not appreciably affected by highly alkaline cleaners. The rest of the non-ferrous metals such as Al, Zn, etc. may be attacked by uninhibited alkaline cleaners. Unless an etched surface is desired, either for appearance or better adhesion of subsequent finishes, a properly inhibited cleaner should be chosen. Aluminum alloys may be subject to even more complicated electrolytic chemistry and should be carefully supervised even in inhibited cleaning solutions.

Having learned a little about soils and surfaces, we are now ready to enter the technical world of cleaners.

METAL CLEANING PART II

ALKALINE CLEANERS (AND ACID CLEANERS)

Milanco manufactures three types of metal cleaners falling into three main categories:
                                                                            1. alkaline
                                                                            2. acid
                                                                            3. solvent

This course will deal mainly with alkaline cleaners, solvents and emulsions and a few acid cleaners. The iron phosphate cleaners which make up the bulk of the acid cleaners are covered in great length in the Phosphatizing Course. In this course, we will cover various metal cleaners, the differences between some cleaners, what to look for during an account survey, how Milanco’s' products are applied, how to choose the right cleaner and electrolytic cleaning.

Alkaline cleaner is a term given to a group of proprietary chemical blends which consists of alkaline salts, wetting agents and sequestering (chelating) agents. Alkaline salts cover a broad group of chemicals including caustic soda (NaOH), caustic potash (KOH), phosphate, silicates, carbonates and borates. This group of materials is said to be alkaline because they fall in the 8 to 14 pH scale. Just what is pH? This term is used often in the chemical industry. Therefore, it is important that you obtain as clear a picture as possible of its meaning, we will endeavor to avoid the chemist's definition which states, in complicated language, that pH is the measure of the INTENSITY of an acid or alkali. Just as amperage is the measure of electrical intensity or temperature the measure of heat intensity, pH measures the degree of intensity of acidity or alkalinity, This definition further states that pH is a numerical Iog function with each successive unit being ten times more intense. lf we wiII look to the accompanying chart, we might be better able to understand the underlying concept of pH chemistry.

The measuring scale of pH runs from 0 to 14 as indicated on the chart. The middle 7 in the series represents the neutral point. Pure water is neutral. Any number below this digit of 7 indicates acidity and any digit above this figure indicates the alkalinity of a solution. As the number get further from 7, the intensity of the acid or alkali becomes greater.

The following examples will give you an idea of how this log function works in practice.

EXAMPLE: If a tank of neutral water (pH 7) takes a pint of acid To bring the pH down to 6, it will take 10 pints to bring the pH from 7 to 5, and 100 pints to bring the pH from 7 to 4, etc. Naturally, the reverse on the pH scale is also true. If 1 pound of alkali increases the neutral pH of a solution to a pH value of 8, it would take 10 pounds to increase the pH from 7 to 9, and 100 pounds for a pH increase from 7 to 10. The factor of 10 continues all the way up and down the pH scale.

ANOTHER EXAMPLE: This factor of 10 is also applicable when neutralizing an acid or an alkali. An acid solution that would take 100 ounces of alkali to change the pH from 2 to 7 would require only 10 ounces to go from 3 to 7, 1 ounce for a change from 4 to 7, 1/10 ounce alkali to go from 5 to 7 and 1/100 for a change from 6 to 7. There are exceptions to this straight log function (10 factor) when certain acids are used because of the buffering action of the salts formed.

Two new words--salts and buffer--have entered our realm of chemistry, and of course, they have need for explanation. A salt is formed whenever an acid and an alkali are mixed,

    HCL         +        NAOH           NACL             +            H20
  Hydrochloric      Caustic         Sodium chloride           Water
    Acid                   Soda           common table salt

One item not indicated in the above reaction is the formation of heat. When an acid and an alkali are mixed a heat of reaction will be formed. Depending on the quantities and concentrations of these chemicals, care should always be exercised in their mixing as violent reactions and bubbling are possible, some reactions bordering on explosiveness.

Another word you will hear from time to time is buffer. We have discussed the formation of salts. Some of these salts resist pH changes in solution and are called buffers.

It's evident, from these examples, that the further the pH is from the neutral point of 7, the more difficult it is to change the pH. This explains why you cannot use pH as an indication of concentration.

            Relative pH values of several alkaline materials:

                                                                                    0.1% Solution-at 80°F
                                                   Caustic soda             12 pH
                                                   Soda Ash                   11.6 pH
                                                   Phosphate                  10.0 pH
                                                   Borax                             8.5 pH

Each of the alkaline materials that are formulated into a cleaner is done so for the specific benefits that are rendered by that particular product. For example:

Silicates - form colloids (solids) which are insoluble but have excellent soil dispersing properties. In the presence of acids these materials become very insoluble and difficult to rinse. This could be highly unacceptable in the electroplating field for example.

Phosphates - noted as good hard water sequestrants Ich ors), excellent dispersion media.

Soda Ash - water conditioning--also provides reserve alkalinity.

Caustic Soda - Workhorse of the alkaline cleaners.

The second general group of chemicals which are incorporated in the make-up of a cleaner are wetting agents. Wetting agents fall into two categories, soaps and synthetic detergents. Soaps are long chain molecules, with one end of the wetter molecule being soluble in oil and the other end being soluble in water and holds the oil in solution by forming an emulsion of the oil droplets in the water. It is important to note that soaps can be made insoluble in hard water which causes them to lose detergency. Synthetic detergents are a large group of various complex chemicals. Synthetic detergents can act like soaps, but basically their job is to make water wetter. By this action, improvement of the penetration of water wettable soils is achieved. A lowering of surface tension at the metal-to-soil bond is facilitated by synthetic detergents. These qualities allow for more efficient and expedient soil removal.

The third and final group of chemicals generally formulated into a cleaner are the sequestering or chelating agents which have two functions:

                1. Softening water which makes for better rinsing and cleaning.
                2. To hold iron or other metals in solution, and keep it from redepositing on the part.

Alkaline cleaners depend on their detergency - lifting the soil from the surface by displacing it with surface active materials which are easily rinsed off - for cleaning.

We have discussed the three major components of a cleaner, especially an alkaline cleaner. But why do I use an alkaline cleaner? What are the benefits, if any?

Advantages of using an alkaline cleaner:

1. Very economical.
2. Acts on a variety of soils.
3. Broad spectrum of alkaline cleaners to choose from.
4. Leaves a desirable surface after cleaning.
5. Rinses with water.
6. Non-flammable.
7. Generally, little waste disposal problems.

Disadvantages of an alkaline cleaner:

1. Usually requires elevated temperatures.
2. Mechanical action necessary.
3. Undesirable effects on non-ferrous metals (caustic on aluminum).
4. Some soils cannot be dissolved by detergent.
5. Possible foam.
6. Slower than solvency.

There are three variable factors which determine cleaning -time, temperature and concentration. A change in any one of these three variables will necessitate a change in the other two. A decrease in temperature will necessitate an increase in time or concentration or both. Likewise, a shortening of the cleaning time will necessitate an increase in temperature or concentration of the cleaning solution. Acid cleaners are blends of mineral acids or their salts, solvents, wetters and inhibitors. The inhibitors control the action of the acids on certain metals. Acid cleaners are used mainly for rust and all types of scale removal.

Milanco manufactures a number of acid products. They basically fall into three types of acids, phosphoric, hydrochloric and sulfamic. These products are used by soaking, spraying or hand application for the following reasons:

1. Rust removal.
2. Heat treat scale.
3. Deoxidizing of metal surface.
4. Dissolving soil solids (boiler hard water scale,      insoluble spray washer scale).
5. Brighten metal.

Here again, we have to consider the pros and cons in deciding whether or not to use this type of cleaner.

Advantages of an Acid Cleaner:

1. Can be economical (energy savings, fast reactivity).
2. Less metal loss.
3. Leaves smooth surface.

The third class of cleaners we will cover is Emulsion and Solvent cleaners. These cleaners can be either straight organic solvents or blends of organic solvents, emulsifiers and wetting agents. These cleaners mainly depend on their solvency (ability to dissolve the soil) for cleaning. Most of them leave a protective film against oxidation.

There are basically three types of solvent based cleaners:

1. Straight Petroleum (aliphatic, aromatic)
2. Non Flammable, Chlorinated
3. Emulsifiable solvents (petroleum solvents and     surfactants and soaps)

The first two work on a straight solvency basis, the ability to dissolve a particular soil. the third class of cleaners works on the mechanism of emulsification which was discussed a little earlier.

In weighing one cleaner against another one should be familiar with the advantages and disadvantages of that particular class of cleaner.

Advantages of Solvent Cleaners:

1. High speed penetration - fast pre-cleaning.
2. Low temperature use - ambient to 150° F
3. Selectivity on certain soils - asphalt, tar, high melting waxes.
4. Loosens varnishes, paints.
5. Fast evaporation - removes excess cleaner from surface, leaves  
    neutral surface.
6. Rust protection can be imparted by some products.

Disadvantages of Solvent Cleaners:

1. High cost
2. Residues may not be tolerated.
3. Flammable, some may be toxic.
4. Unsuitable for some soils.
5. May require special equipment.
6. Waste disposal could be a problem.
7. Buffing compounds - removal of a soluble component may leave inert
    abrasives which can become extremely difficult to remove in final
    cleaning. The use of slow solvents is recommended here.

IRON PHOSPHATE COATINGS

The first question you might ask is "Why Phosphate?" There are three major reasons why phosphating can be beneficial to your operation:

1. Form a stable inert coating on the metal surface
2. Provide excellent paint adhesion
3. Inhibit the spread of corrosion from a damaged area

Phosphate chemicals are mildly acidic solutions containing accelerators and surfactants. They can be applied over a wide temperature and pH range. The coating weight of phosphate can vary from 15 milligrams per square foot to 100 milligrams per square foot depending on the process used.

The process of choosing a phosphate for a specific use is based on the following considerations:

1 . Type of metals or plastics to be prepared, cold rolled steel, hot
      rolled steel or aluminum.
2. Cleaning requirements: type of oils or soils and amounts present on the surface.
3. Type of coating to be applied and method of application:
    a) Solvent based paint
    b) Powder application
    c) Electrodeposition
4. Temperature availability
 

The method of application is a key factor in determining what type of phosphate will provide the best results.

In a five-stage washer, the phosphate will normally be applied in the third stage. It is preceded by an alkaline cleaner in the first stage to remove all the contaminants from the surface. The second stage would be an overflowing fresh water rinse.

Rinsing is very important for two reasons. First, you want to make sure all the contaminants are removed from the surface. You can't get a good phosphate, unless you have a clean surface. Secondly, you want to make sure the chemical from stage one has been removed. This will prevent cross-contamination and eliminate chemical carry-over from one tank to the next. Stage four would be a fresh water rinse and stage five would be a water rinse or seal, preferably a seal. This final seal will give you even greater corrosion protection.

In a three-stage washer, the phosphate will be applied in the first stage. Since the phosphate will be responsible for both cleaning and phosphating the part, the phosphate used would have an enhanced surfactant package. It would also have additional accelerators, which would increase the performance of the phosphate. Stage two would be an overflowing fresh water rinse and then a seal in the third stage.

Two other methods of application are dip tanks and steam cleaning. In a dip tank operation, the parts are placed in a basket and lowered into the solution for a pre-determined amount of time. The biggest advantages of a dip tank operation are that you are able to run larger and more complex-shaped parts that you normally might not fit in a spray washer. The second advantage is the lower start up costs, as compared to a spray washer.

Steam cleaning is good for small volume manufacturers and large parts that might be hard to handle. A steam jenny normally can be adjusted to provide the right concentration of chemical. You spray the part from the bottom to the top. This will help eliminate streaking and give you a better appearance. This process would be followed by a fresh water rinse.

There are several ways to phosphate a part. The type of equipment you need will depend on the volume of work you are processing, the size of the parts you are producing, and the space constraints of your facility.

The next step is determining the quality of the phosphate on the part. There are several ways to do this. The least scientific of which is by looking at the color of the part. The chart below gives a comparison of color and how that relates to coating weight.

The next two procedures are tests that can be perform after the parts have been painted. The first test is a "cross-hatch" test. This test involves scribing eleven lines up and down and side to side to creating a small grid that has 100 squares. You then take a piece of clear tape and apply to the grid. Remove the tape and see if any paint comes off on the tape. This will give you a good indication of what kind of paint adhesion you have on your parts.

The next test procedure is salt spray test. The test can be performed in an independent laboratory. You can run the test for any number of hours you want. This would depend on what specifications you have to meet. The standard length of the test is 96 hours. These tests are usually performed on small test panels. The parts are scribed down the middle so you can check for blistering from the scribe and along the edges. Coating weights are not directly proportional to salt spray results. The purpose of this test is to check for paint adhesion and the amount of corrosion protection.

In order to get the best possible phosphate, you need to be able to control the phosphate bath. The washer operator has the responsibility of maintaining several things. Some of these are concentration, tank levels, pH and temperature, spray pressure, nozzles, risers, and screens.

The concentration of the phosphate bath is the percentage of chemical in the tank, The concentration can be affected by a couple of factors. The two main reasons are chemical carry out and loss of water due to evaporation. The phosphate can be added manually by the operator or a small diaphragm pump can be installed to automatically add small amounts of chemical throughout the day.

The tank levels are usually maintained automatically by low level and high level switches. When the water level gets to a certain point, a level control switch will activate a pump that will add fresh water. The pump will add water until it reaches the normal operating level.

The pH of the phosphate needs to be maintained between certain parameters. This depends on what type of metals you are phosphating. Generally lower pH materials are used on hot rolled steel and weldments, middle range (pH 4.5 to 5.2) on cold rolled steel and higher pH ranges (5.4-5.8) afford maximum coating deposition in ranges of 70 to 80 milligrams per square foot. The ideal temperature range for a phosphate bath is between 110-160°F.

The type of spray nozzles used effects the performance of the phosphate bath, For the phosphate stage, flat fan nozzles with a capacity of 5 gallons per minute at 20 psi are recommended, since they have less of a tendency to clog. Never use nozzles smaller than 2 gallons per minute at 20 psi unless your pump capacity is too small to support them.

The phosphate bath will have to be dumped on occasion. The frequency of these dumps depends on several factors. The amount of work sent through the phosphate bath and the contamination on the parts.

When you phosphate a part, you are slightly etching the surface. This means you are removing metal from the surface of the part. These small particles that are removed are then re-deposited on the part in an irregular fashion. This provides a surface that the paint will better adhere to. The side effect of this is that some of the metal that is etched off will not be re-deposited. Therefore, these particles will remain in the tank in the form of phosphate sludge. As this sludge accumulates in the bottom of the tank, it will become necessary to dump the tank and remove this sludge build-up. Equipment can be installed on the phosphate bath that will help extend the intervals between tank dumps. For example, a filter press can be very useful in extending the bath life of the phosphate.

The contamination issue is less of a factor in a five-stage washer than in a three-stage washer. In a three-stage washer, the phosphate is performing both the cleaning and phosphating. Therefore, the contaminants that are washed off will be held in solution. An oil/water separator is a good way to remove contaminants that are held in solution. If the phosphate is designed to kick out the contaminants to the top, an oil skimmer would be an effective way to remove them.

Milanco Polymer chemicals are used in systems that separate undissolved contaminants from waters. These waters can be the influent (water flowing in to a plant), process (water used and recycled in he plant) and wastewater (flowing out of the plant).

INFLUENT CLARIFICATION

Less than 3 percent of the water found in nature is usable as is. This usable supply, which includes clear lake waters, some clean rivers, and some well waters, is a fairly fixed commodity pressured by an increasing usage by mankind. These usable waters often must be cleaned up prior to human and industrial consumption. City water works remove pathogenic and slits from the water processed for consumers. To enhance product taste, beverage bottlers treat water they draw from the city. These treatment processes include influent clarification (separating solids in and from the incoming water).

PROCESS WATER CLARIFICATION

When large volumes of water are used to wash and rinse off the commodity being processed, that producer usually has a concern for the cost and quality of the water he/she is using. First they ask themselves if they can use fresh water. The answer depends upon the type of dirt or contaminant that is in the used water.

For example, a large paving or construction company may wash sand and undesirable fines off quarried stone being crushed and sized. The dirtied water enters a holding containment where the undesirables settle out. then the cleaner or clarified water is used again. Processes such as mining, steel making, asphalt/paving, and paper production employ techniques to clean up and reuse process waters.

WASTEWATER CLARIFICATION

Most processes that generate dirtied, contaminated water find that processing that water to a quality acceptable for their own reuse is more costly than discharging it as wastewater. After all, wouldn’t it be more costly for you to clean up your dirty bath water at home than to empty it to the sewer and use clean city water for your next bathing?

Municipalities provide sophisticated Publicly Owned Treatment Works (POTW’s) to clean up wastewaters that households and industry alike discharge to the sewers. The microorganisms at work in these POTW’s turn dirty water in to water clean enough to discharge into a river without upsetting the balance of aquatic life.

Most POTW’s are designed to treat household and light industry wastewater. The contaminants present in process industry wastewater could be harmful to the microorganisms at work at the POTW. POTW’s, through regulatory agencies, establish maximum levels at which harmful contaminants can be present in an industrial wastewater discharged into the POTW’s receiving sewers.

Industrial facilities must remove polluting contaminants such as toxic metals, oils and grease and chemicals from its wastewater before it can be sewered. In essence, industry pretreats its water before discharging to a final treatment plant, the POTW.

APPLICATIONS

Each industry generates its own type of contaminating solids. Fats and oils tend to float on water, while denser solids, like sands, will settle. Large masses separate rapidly in water. usually solids are encountered as a very fine suspension slow to either float or settle in water.

Separation Polymer products act like chemical magnets, attracting finely suspended solids into larger masses which separate much faster in the water.

Though there are many types of solids to be separated from water, the systems are basically designed to separate the solids from water after allowing them to either float and/or settle. When solids still resist these tendencies, a system may be designed to filter out the solids.

METAL FINISHING INDUSTRY

Waters used to rinse parts accumulate contaminants which must then be separated from the water before it is sewered. For example, after each stage in which a part is cleaned, plated or otherwise treated it is rinsed off. Oils, toxic metals like zinc, copper,and cadmium, cleaners and soils must be separated from those dirtied rinses before they are sewered.

The contaminants are separated out as the waters flow through a series of tanks in a treatment system. In the first tank, floating oil is skimmed off. In the second the chemistry of the contaminant water is changed. In the third the settleable solids do so and are removed as sludge. The water itself is then allowed to flow to a sewer.

Your chemicals help separate emulsified oils, chemically precipitate and coagulate solids, and efficiently separate those solids by flocculation to achieve water clarity.

FOOD PROCESSING INDUSTRY

The large volumes of water used to keep these facilities and the food clean often must be treated to remove contaminants before the water can be discharged to a sewer.

In a plant that slaughters hogs, cattle, or poultry, fat and blood that end up in rinse waters must be separated out before the water can be sewered. The contaminated waters flow into large tanks. There fats float to the surface and are subsequently removed by skimming. The blood is also removed after it is chemically treated.

Separation Polymers are used to improve upon the rate of floatation or settling of fats, oils, greases and soils.

AGGREGATE PROCESSING

Large volumes of water are used to wash very fine soils off gravel or stone. Processors are interested in removing the fines from the dirtied water so that the water can be reused.

Typically the dirtied wash waters are allowed to stand in large holding basins so that the fines settle to the bottom. The cleaner water is then reused. Polymer flocculants can be added to the dirty water as it enters the pond. The polymer makes the slow-to-settle fines come together in a larger, more rapid settling mass. This allows the processor to reuse the improved water sooner.

BASIC SEPARATION POLYMER PRODUCT LINE

Most of the applications that you will be exposed to use Separation Polymer products to perform one of two functions, coagulations or flocculation, of suspended solids.

Normally, solids finely suspended in water are first coagulated into somewhat larger pinpoint-like masses then flocculated into even larger snowflake-like masses.

The basic chemical theory that we use is attracting solids with a chemical magnet. The terms anionic and cationic are used to define the magnetic change which distinguishes one product from another.

Products are available in three physical forms; liquids, liquid-emulsions and powders.

Let’s talk a little about where Liquid Solids Separation technology can be used and the technology itself.

The following example illustrates some basic ways our prospects separate contaminants from water.

Imagine adding instant hot chocolate mix and marshmallows to a cup of hot water. Some solids are readily dissolved and some are not. Momentarily stir the imaginary contents then let the cup stand.

The marshmallows float to the surface of the mixture. Flotation is one way to achieve separation of undissolved solids settle to the bottom of the cup. Settling or sedimentation is another way of separating undissolved solids from a liquid.

Pour the hot chocolate through a coffee filter. Filtration is yet another way of separating undissolved solids from a liquid.

Industry uses flotation, sedimentation and filtration to separate undissolved contaminants from volumes of dirtied water.

Your Milanco Polymer products help these techniques work better.

TECHNIQUES FOR REMOVING
DISSOLVED CONTAMINANTS

But what about dissolved solids? If we had removed all of the undissolved solids in our imaginary cup of instant hot chocolate, it would still taste more like hot chocolate than water. We know that there are some dissolved solids still in the water.

There are techniques for removing dissolved contaminants from dirtied water. Sometimes dissolved solids can change to their undissolved form and be removed as described above. This is called precipitation render the contaminant harmless.

Some dissolved solids and other forms of contamination can be removed from the water only by biologically changing them to a harmless state. Municipal treatment plants usually perform this service because it’s to costly and impractical for each industrial generator to do it. But,

BASIC TECHNOLOGY
PRECIPITATION-COAGULATION-
FLOCCULATION-CLARIFICATION

There are basic technical explanations of the physical and chemical elements that you will be exposed to.

Our chemical objective is to enhance the separation and removal of undesirable suspended solids from water. The industrial plant must have a system that, at some stage, allows those suspended solids to be separated by flotation, sedimentation or filtration. Usually these techniques clarify the water.

Problem solids may initially be dissolved or undissolved in the water. However, they can be removed only if they are in their undissolved state as particulates or suspended solids. Treated water clarity might tell us how effectively the chemicals are working, but only lab analysis can tell us levels at which contaminants remain.

Let’s generalize the Milanco technical approach:

"Chemicals for precipitation, coagulation and flocculation greatly enhance the clarification of suspended solids-laden waters in sedimentation or flotation systems."

• Precipitation
• Coagulation
• Flocculation
• Separation
• Clarification

But what do these terms mean? Let’s explore them a little more in depth to get a feel for just what it is that we have and what we are trying to achieve.

PRECIPITATION

Dissolved solids can change to their undissolved form in a process called precipitation. The precipitated, undissolved solids are called particulates or suspended solids.

Water in which all the solids are dissolved will appear to be clear. The appearance of the solution of partially or totally precipitated, undissolved solids will vary. It could be slightly hazy to milk white/chocolate in clarity and have a water-thin to milkshake-thick consistency. Particulates can be any color.

Why would dissolved solids change to their undissolved state? What causes precipitation to occur?

For our purposes, the addition of a chemical precipitant like caustic soda, lime, or sulfuric acid, will change the pH of a solution of dissolved solids. Simultaneously, a reaction which yields the undissolved form of the solids occur.

COAGULATION

Some solids, like sand and gravel, will settle very quickly in water. And some, like the marshmallows in our cocoa example, float readily. In general, solids heavier or denser than water sink in it and solids lighter than water float in it. (You may be aware that specific gravity is a measure of relative densities.)

But, solids with densities close to that of water remain in suspension. It may take hours, days, and even years for some types of solids to separate from the water. If they would come together or coagulate into a larger mass, that mass would separate more rapidly in the water.

A simple explanation addresses this phenomenon. Certain particulates have a predominance of negative surface charges. Think of the adage, "opposites attract and likes repel". Like similar ends of a magnet, solids with like charges repel each other and resist coming together or coagulating.

Chemicals can be used to cause coagulation. The molecules of these chemical coagulants have a predominance of surface charges opposite those of the particulates that we would like coagulate.

When these chemical coagulants are introduced into water, they provide opposite charges that neutralize or destabilize the problematic charges. Opposites attract and coagulation takes place.

In comparison with the milkish fine suspension of precipitated solids, coagulated formations are a more readily distinguished pinpoint size. technically we call them pinflocs.

FLOCCULATION

Though solids in coagulated masses or pinfloc precipitated solids, a final step is needed to make the mass even larger and subsequently faster in separating.

This final step, flocculation, is caused by introducing a long-chained polymer molecule to which numbers of pinflocs can attach. This molecule again has a predominance of charges on its tips, but these charges are opposite those of the coagulating chemicals.

The polymer flocculant will gather enough pinflocs together to form increasingly larger masses like large snowflakes. The buzz phrase here is that the flocs grow.

SUMMATION

These are basic technical explanations of the physical and chemical elements that you will be exposed to. Let’s review what we just covered.

Our chemical objective is to facilitate the removal of undesirable suspended solids from liquid, normally water. The industry must have a system that, at some stage, allows the suspended solids to be separated by flotation, sedimentation or filtration.

Problematic solids initially may be dissolved or undissolved in the water. However, they can be removed only if they are in their undissolved state...suspended solids.

The Milanco technology encompasses four basic steps that absolutely must be in place.

SEPARATION/CLARIFICATION

When enough of the pinfloc masses have been pulled together into a large snowflake-like floc mass, the floc formed will settle or float. These settled or floated masses are then removed as sludge or skim and the clarified water discharged to the sewer or reused. Sometimes an additional filtering step may be in place to remove the trace solids that remain.

A PERSPECTIVE ON CHARGES

The terms anionic and cationic describe the charges that were discussed. Readily verbalize your product as anionic or cationic. You are rarely asked to explain the terms. The only way to practically determine the charges on problematic solids is the actual pinfloc or flocculant that forms when you add your product. At least 90 percent of the time, cationic products help form pinfloc and anionic polymers achieve flocculation and clarity.

PRECIPITATION

Solids change from dissolved to undissolved, particulate state, becoming visible suspended solids.

COAGULATION

The addition of favorable charge sites neutralizes resistance of suspended solids to being applomerated. The result is formation of distinguishable pinflocs.

FLOCCULATION

The addition of a long-chained polymer molecule that attracts the pinfloc into a large snowflake-like formation.

SEPARATION/CLARIFICATION

The stage at which the large flocculant floats, sinks or is readily filtered.

OVERVIEW

The objective of the operation of most treatment facilities is clear water. More importantly, though, a successful application means clear water that meets environmental standards.

The primary concern of most wastewater treatment operators is compliance with government regulations. Helping system operators meet that objective is a major opportunity for making a sale.

PRECIPITATION

Precipitation involves the change from the dissolved form into an undissolved, particulate form. In order to settle (or float) suspended solids from water they must be precipitated from the dissolved form into the undissolved form.

Two precipitation phenomena are of specific interest in liquid/solids separation systems:

a) Precipitation of contaminants to be removed from the system, and

b) Precipitation of inorganic salts of which chemical coagulants are made.

METAL CONTAMINANTS THAT
PRECIPITATE IN THEIR
HYDROXIDE FORM

If toxic heavy metals like zinc and copper are in the wastewater, those metals must be in their precipitated state before they can be separated from the water. Normally that state is called its hydroxide state. As an example, zinc precipitates as zinc hydroxide.

In the wastewater there is a pH point at which the metal present is best precipitated as a hydroxide. To effect precipitation, the pH of the untreated wastewater is adjusted to and controlled at a preset pH point by adding chemicals.

Calcium hydroxide (lime) and sodium hydroxide (caustic soda), are often used to cause the necessary upward change in pH. Sulfuric acid is often used to change the pH downward. The precipitated metal hydroxide is then coagulated, flocculated and separated from the water.

Our examples depict the metal ion precipitating when the pH of the water that it is in changes. (The curves are often referred to as metal solubility curves.)

On the vertical axis the amount of metal that is present is measured in ppm. The horizontal axis shows the pH of the solution.

In Figure 1, as the water pH increases from 6 to 9 pH, the metal ion precipitates out as a metal hydroxide. At the bottom point of the curve the metal is as precipitated, insoluble or undissolved as it will become.

Note that the curve starts upward again as the pH is raised from 9 to 12 pH. This shows that the metal ion starts to redissolve. Of course a dissolved ion can’t be separated out.

Figure 2 illustrates precipitation curves of several heavy metals. Each metal has a different pH at which it is most precipitated or least dissolved.

In a metals removal system pH control points often reflect a compromise with how the metals precipitate and how much metal is present in a particular system. The ultimate control point is the point at which the metals removal is most favorable.

There are chemicals used in some production process waters that may chemically combine with a metal ion and then interfere with that metal’s normal precipitation tendencies in the wastewater treatment system. They are called chelants or complexing agents.

Figure3 compares precipitation curves of just such chelate/copper ions with copper ions that have not been exposed to chelants.

Notice how the chelated copper doesn’t precipitate as well at the pH where the non-chelated are present, some of the metals remain dissolved in the water and pass through the system regardless of pH.

PRECIPITATION OF METAL
IONS PRESENT IN COAGULATION

Remember our principles: precipitation-coagulation-flocculation.

After the metals have been precipitated out they sometimes will coagulate on their own.

But, as we described earlier, precipitated solids usually have a predominance of the same surface charges and resist coagulating by themselves.

Chemical coagulants may have to be added to facilitate coagulation, flocculation and separation.

Some chemicals that are used to coagulate suspended solids are actually formulated from metals such as iron and aluminum. Those metals must also be precipitated so that they can cause coagulation.

In figure 4, the precipitation curves of two such metallic coagulants, alum and ferric chloride, are illustrated. Again, note that they are most precipitated in a certain pH range. That range of pH is where they function best as coagulants.

Figure 5 shows their coagulation potential capabilities. (The precipitation curves have simply been inverted.) Note that the potential for coagulation is at a maximum in a well defined pH range.

This process also reflects a change of chemical form or change of the metal ion, a technicality beyond the scope of our discussion.

PRECIPITATION CURVES FOR
COMMON HEAVY METALS

On the following page, you will find an exhibit depicting the precipitation curves of common heavy metals. This exhibit will serve as an invaluable reference when you are assessing pH controls.

OCCURRENCE OF PRECIPITATION
IN A TREATMENT SYSTEM

In a continuous system, you will find precipitation occurring in a tank called the Neutralization of pH Adjustment Tank.

Often, this is the same tank in which coagulation occurs.

You should now be routinely thinking; Precipitation-Coagulation-Flocculation-Separation. Well, people often erroneously feel that flocculation most influences separation. When he solids aren’t separating right the polymer flocculant is often suspect. But, you already know there is more to it than that.

So what do you do when a industrial operator points out that there are solids in a clarified water sample, no clarification in the clarification stage, or no flocculation in the floculation stage? What if the operator says "...the floc (polymer flocculant) isn’t working"...

Think it through logically. the operator may feel that the quality and appearance of the treated water is the problem and the polymer flocculant is causing it. But in poor flooculation or separation you really see symptoms of the problem. First find the real problem, then what is causing it.

Many problems have symptoms have symptoms that show up in the quality and appearance of the treated water. The polymer flocculant choice could be the problem, so could the chemical choice for precipitation or coagulation. But, most often a problem with those symptoms is either a system malfunction or a change in the untreated water that has rendered the treatment procedure ineffective.

THE SYSTEMS APPROACH

Consider a systems approach. When surveying, starting up your program, address the whole system, even if it;s running well.

Let’s use some common sense. Every system in some make, shape or form, is trying to make your technical concept work. Remember; Precipitation, Coagulation, Flocculation, Separation.

So, a good common sense approach is to:

1) Identify where and how these functions occur.

The engineer or the operator should know how to run the system. There also may be a cookbook around that contains invaluable details laid out by the folks that first put the system together. Nail down all of these design criteria.

2) Determine if those functions are occurring properly.

Ask around. "How does this stage look when the system runs good?" "Just what is wrong with the way this stage is running now?" (The stage is where the function occurs.) Ask for visual and even analytical input.

Your operator might respond..."Usually we get a popcorn-sized floc(culant)."

Or, as we mentioned earlier, these questions may produce visual symptoms of the problem..."The floc(culant) isn’t forming. See how murky the water is?"

3) Ask what is done to maintain or resolve the condition.

"What do you do, at this stage, to keep the system running right?" "When this stage hasn’t functioned right, what have you tried?"

4) Check for recent changes in the production process.

Changes in the production end of operation could be influencing the naute of the untreated water.

5) Assess the treatment chemicals in use.

Check out the chemicals that you are using. You know some ordinary things to do: kick the drum--maybe it’s empty, check the chemical feed pumps--they could be inoperable or set incorrectly, maybe the lines are plugged or broken. Make sure that the chemicals are being prepared, diluted and generally used the way they’ve been specified.

Now let’s get to where the real action is. You can play chemist. You can test the untreated water to determine what the appropriate chemical selection and usage rates should be. In this way you determine the treatability of the water.

ADVANCED TROUBLESHOOTING

This Troubleshooting Guide was developed based on professional publications and years of Milanco experience with industrial pretreatment systems.

The factors addressed are also evident in industrial treatment systems of a non-biological nature discharging directly to a natural receiving water. Many of factors are even evident in biological treatment systems.

CONTROL AND MAINTENANCE OF COOLANTS

Product Selection as seen in Lesson #2 is very important. Certain products simply will not perform a particular machining or grinding operation. Other products are not safe to use on certain metals. And in many jobs there are a number of products that will do the job, but one type works best. This product increases production, increases tool life, reduces rejects, makes for more pleasant working conditions, and saves money and increases profits overall, So it is essential that you choose the best product available for the machining and/or grinding operations in your accounts.

Let's now assume that you have selected the right product and the right product concentration. You're definitely off on the right fool, but you're still far from a smooth-running cutting fluid account.

After you have chosen the product and mixing dilution, the first thing to do is clean the machine or machines. Putting fresh new coolant into a dirty sump is asking for problems; You have most likely gotten a shot at this account: because you've convinced the engineer or maintenance foreman that you could solve a particular problem. And most probably the reason for his problem was bacteria and tramp oil. (Tramp oils are a combination of oils from the work and the machine which end up in the cutting fluid.) Don't put clean coolant into a dirty machine. If you do, chances are you will not solve his problem and you won't have an account very long. Insist that they take the time to clean the machine with MACHINE SUMP CLEANER prior to charging with fresh coolant.

MACHINE SUMP CLEANER mixed 1 part to 25 parts water will do a very nice job of cleaning the coolant tank. Allow the MACHINE SUMP CLEANER to recirculate in the system a minimum of two hours. However, the longer the cleaner is recirculated the better. Do not compromise in this procedure, for it is very important. After the MACHINE SUMP CLEANER has recirculated a minimum of two hours, drain the MACHINE SUMP CLEANER from the tank and rinse twice with clean water. Any residual MACHINE SUMP CLEANER can cause foam problems in the cutting fluid. So it is important to remove all the MACHINE SUMP CLEANER from the tank.

Immediately after the second rinse, charge the tank with the selected coolant. If you are charging the system manually, fill the tank with water and add the cutting fluid slowly to the water where there is the most agitation. A better way to charge the tank is via one of Milanco’s automatic dispensers.

Once the tank is filled, even if you have used one of the automated dispensers, check the coolant concentration. This can be done using either the Milanco Lubricoolant Titration Kit or a Refractometer. Charts for both the Titration Kit and the Refractometer are available for all Milanco coolants (Cutting Fluids).

The first two weeks after installing a new coolant are very critical. Service is always important, but never more important than during these first two weeks. You must check the concentration daily for the first three days. This is a new coolant, and unless you are there the machinists will treat it the same as they did the old coolant. During the first week, you will get a feel for how the coolant runs. If you want to run a coolant at a 1 to 20 ratio, you cannot continually add make-up at 1:20. Water is continually evaporating from the system, which will increase the concentration. The coolant concentrate does not evaporate. Coolant is lost only through carryout on the parts, splash out and leaks in the tank. So if you want to keep a system at 1 to 20, your make-up should be in the 1 to 40 range. The first two weeks will give you a good idea of just how much concentrate is required to maintain concentration.

Remember, if you charge the tank with a drum proportioner set at 1:20, you cannot continually make up to that tank at 1:20. It will soon be 1:10 and continue to increase in concentration. Set the proportioner at 1:40 by changing the orifice and see how it runs for the first week or two.

After deciding on the proper make-up, you must periodically check the system and the proportioner with the titration kit or refractometer to make sure they stay in line. A coolant system out of line for only a day or two can cause problems!

Cutting fluids are designed to run in the tanks with a pH above 8.5. If the pH drops below 8.5 something is wrong arid you are asking for rust and rancidity problems. Most Milanco products when first added to the machine will have a pH between 9.0 arid 9.5. This initial pH will drop because of carbon dioxide which is picked up from the air. The pH should buffer out between 8.5 and 9.0. This is the optimum pH range to run a coolant. It is high enough to aid in rust and rancidity control and not too high so that it causes dermatitis problems.

Check the pH. If it gets too low, something is wrong. Either acid contaminants or bacteria are getting into the system, or the concentration is too lean.

We have pH paper available for checking pH and lubriculture sticks for checking bacterial levels. Use these items to help you control your cutting fluid systems.

Good housekeeping is also important. If tramp oil is allowed to build up in the tank and this tank sits over a weekend or holiday, you are most probably going to have bacteria problems. Educate your employees, impress upon them the importance

of skimming tramp oil off the tank. It takes little time to do and can make a big difference in how well a coolant performs.

If your machine is having problems, it is important that you learn about them as soon as possible. Check some of the parts to see if there is any rust, ask the operators how the coolant is doing, and check the coolant usage level. Find out why they used more or less this week than last.

Service is part of the Milanco deal. Service is something they probably did not get from the competition, and this lack of service is probably the reason they've had problems. We give the service he deserves needs.

Milanco has cutting fluid additives which can solve a lot of problems and save a lot of accounts. Have some additives on hand at all times and don’t be afraid to use it. Earlier I talked about the importance of maintaining pH. Milanco additives not only will increase the pH to about 9.0, but it will have a buffering effect on the pH which will help to keep that pH around 9.0. Additives, as we all should know by now, kills rancid odor immediately, but it also has an effect on the bacteria causing these odors. Because additives increases the pH and improves the quality of emulsions, it makes the coolant much more resistant to future bacteria problems.

The new Resource Conservation and Recovery Act makes it very difficult now to dispose of coolants. Therefore, anything you can do that will reduce the amount of coolant a machine shop has to dispose of will save them money and headaches. Concentration control, pH control, good housekeeping, dispensing equipment, and additives will help to prolong tank life and reduce disposal problems and costs.

COOLANT SELECTION

Now that we know what type cutting fluids are available, it is time to learn where to use the various types. First, however, let's list some of the qualities required in a good cutting fluid.

1. Good lubricating qualities to reduce friction and heat and therefore
     improve the machining/grinding action of the tool.

2. Good cooling action to dissipate the heat effectively that is generated
     during the metalworking process.

3. Effective anti-weld qualities to prevent metal build-up on the too!
     which reduces tool life.

4. Good wetting characteristics which allow the fluid to penetrate better
     into the cutting area and therefore lubricate and cool better. Good
     wetting also helps with rust control because it spreads out the
      inhibitors better on the metal surfaces.

5. Resistance to rust and corrosion via inhibitors built into the fluid.

6. Resistance to rancidity by using effective biocides and other rancidity
    control additives.

7. Relatively low viscosity fluids to allow metal chips and dirt to settle out
    and be flushed away from the work area.

8. Does not leave a sticky or gummy residue on parts or machines.

9. Stable solution or emulsion.

10. Non-misting to insure a safe working environment.

11. Non-toxic to insure operator safety.

12. Non-flammable and non-smoking.

13. Easy to filter and dispose.

14. Biodegradable so as not to harm the environment.

15. Economical.

If there was one product that met all the above mentioned requirements the selection of a cutting fluid would be easy. But there just is not such a product.

As is so often the case, each cutting fluid has its advantages. Each product has its place. Let's now compare the qualities of the four groups and find out where each works best.

           Straight Cutting Oils
            Advantages

            1. Good lubricity
            2. Effective anti-weld qualities
            3. Good rust and corrosion protection
            4. Do not go rancid
            5. Form stable solutions
 

            Disadvantages

            1. Poor cooling
            2. Mist at higher speeds
            3. Flammable
            4. Smoke at higher speeds
            5. Not biodegradable
            6. Expensive to use

Straight oils perform best in heavy duty machining operations and very critical grinding operations where lubricity is very important. These are generally slow speed operations where the cut is extremely heavy. Some examples would include broaching, threading, gear hobbing, gear cutting, tapping, deep hole drilling and gear grinding. Straight oils do not work well in high speed cutting operations because they do not dissipate heat effectively. Because they are not diluted with water and the carryout rate on parts is high, these oils are costly to use and, therefore, only used when a water dilutible fluid will not do the job or the machine tool is not designed to handle water dilutable products.

           Water Emulsifiable Oils
            Advantages

            1. Good lubricity
            2. Good cooling
            3. Effective anti-weld qualities
            4. Adequate wetting abilities
            5. Good rust and corrosion protection
            6. Non-toxic
            7. Non-flammable
            8. Economical
            9. Low viscosity

           Disadvantages

            1. Rancidity
            2. Emulsion stability
            3. Misting
            4. Disposal
            5. Not biodegradable

Water emulsifiable oils are the most popular cutting fluids in use today. Because they combine the lubricating qualities of oil with the cooling properties of water they can be used in a wide range of both machining and grinding operations. Milanco products can be used for most milling, turning, drilling, reaming, boring and sawing operations. They provide good cooling for high speed production operations and are safe to use on both ferrous and non-ferrous metals. When machining soft metals like aluminum, an emulsifiable oil is almost always recommended.

Rancidity has always been the big problem with emulsifiable oils and the major reason for the development of the synthetic. Another more recent problem is disposal. Milanco feels, however, that products which form stable emulsions and are formulated with rancidity control additives, greatly reduce these problems. When you combine these quality products with good service, control, filtration and additives, have the best cutting fluid system available today.

                    Synthetic Fluids
                    Advantages

                    1. Adequate lubricity for grinding and light to medium  
                        machining
                    2. Excellent cooling
                    3. Good wetting
                    4. Good rust protection
                    5. Resistant to rancidity
                    6. Low viscosity
                    7. Stable solution
                    8. Very little misting problems
                    9. Non-toxic
                    10. Completely non-flammable and non-smoking
                    11. Easiest of all types to filter and dispose
                    12. Biodegradable
                    13. Economical dilutions

                    Disadvantages

                    1. Insufficient lubricity for many heavy duty applications
                    2. Metal safety on non-ferrous parts
                    3. Residue can sometimes be a problem

Synthetic coolants provide many advantages as you can see from the above list. When considering water dilutable fluids, synthetics are by far the most resistant to rancidity. This one quality is probably the major reason so many shops have changed to synthetics in recent years. The excellent cooling qualities provided by synthetic fluids make them a popular fluid for noncritical grinding operations on steel and cast iron where cooling and rust control are of major concern.

These synthetic fluids are completely non-flammable because they are water based concentrates, most are biodegradable and they are generally very easy to filter.

As disposal problems become an ever increasing problem with the advent of the Resource Conservation and Recovery Act, synthetic fluids, because they present less of a disposal problem than emulsifiable oils, will become more popular. It is important, however, to understand that synthetics do not completely eliminate disposal problems. They too must be treated before they can be disposed. Generally speaking, synthetics are easier to treat than emulsifiable oils; and because they are more resistant to rancidity they last longer in the machine tool sumps. Therefore, the volume of coolant that needs treatment is greatly reduced.

Synthetics are most definitely the products of the future. A very large percentage of the development work on cutting fluids is devoted to improving the synthetic fluid technology. However, there are still some problems and still some machining and grinding operations that for one reason or another cannot be done using a synthetic fluid.

Lubrication has always been the big problem for synthetic coolants. There are still many so called "heavy duty" machining operations and "critical" grinding operations whose lubricity requirements are more than what the synthetic fluid, without oil, can provide. These heavy duty machining operations are typically the slow speed or intermittent cutting operations like threading, tapping, broaching, and gear hobbing. Also, the more difficult to machine metals like stainless steel and many high temperature alloys require more lubricity than the synthetic can provide.

Another problem caused by synthetics is the sticky and gummy residue that is sometimes left when water evaporates from the solution mix. This can cause parts to stick together and moving parts to "freeze" on the machine tool. With improvements in synthetic lubricant technology, however, this is becoming less of a problem.

Metal safety on non-ferrous metals is a problem with some synthetics because of their relatively high pH (8.5 to 10.0) and the lack of oil to act as an inhibitor. Softer, non-ferrous metals like aluminum also tend to build up on the tool more with synthetics than with emulsifiable oils. When this happens, tool life is reduced; and it is difficult to hold finish and tolerances.

As a general rule, use synthetic products like MD-SYN for surface grinding operations on cast iron and steel. For most cylindrical and centerless grinding operations on cast iron and steel use HD-SYN. The cylindrical and centerless grinding operations generally require a more critical surface finish and closer tolerances and, therefore, the lubricity requirements are more severe.

For light to medium duty machining operations like milling, turning, boring, drilling, reaming and sawing on steel and cast iron, use HD-SYN.

Synthetic fluids work very well in the grinding and machining operations just mentioned but, as a general rule, should not be recommended for grinding and machining jobs on non-ferrous metals or the harder to machine alloys like stainless steel.

Since Milanco makes a number of semi-synthetic cutting fluids, I will not spend time discussing the advantages and disadvantages of semi-synthetics. It will suffice to say that if you need to replace a semi-synthetic fluid, analyze the operation (metals being worked and types of machining and/or grinding) and recommend either a synthetic fluid or an emulsifiable oil, whichever fits best.

The following chart lists the various types of machining and grinding operations, the most commonly worked metals and the recommended Milanco coolant. When using the recommendation chart note the following:

1. Not all applicable Milanco products are listed on the chart. Where the chart recommends Nitrite, you could use HD-SYN if a non-nitrited product is necessary.

2. Where the chart lists S.O., this means a straight oil is recommended.

As with all charts of this type there will be exceptions, but this recommendation chart should greatly assist you in your selection of the proper cutting fluid.

TYPES OF COOLANTS

When you hear someone mention the term cutting fluid these days, that person is most probably referring to one of the four major types:

1. Straight Cutting Oils
These are oil based materials which generally contain what are called extreme pressure or anti-weld                additives. These additives react under pressure and heat to give the oil better lubricating characteristics. These straight cutting oils are most often used undiluted. Occasionally they are diluted with mineral oil, kerosene or mineral seal oil to either reduce the viscosity or the cost. They will not mix with water and will not form an emulsion with water,

2. Water Emulsifiable Oils
More commonly referred to as soluble oiIs. This, however, is a misnomer because they are not really soluble in water but rather form an emulsion when added to water. These emulsifiable oils are oil based concentrates which contain emulsifiers that allow them to mix with water and form a milky white emulsion. Emulsifiable oils also contain additives similar to those found in straight cutting oils to improve their lubricating properties. They contain rust and corrosion inhibitors and a biocide to help control rancidity problems.

3. Synthetic Fluids
Sometimes referred to as chemical fluids, these synthetic cutting fluids are water based concentrates which form a clear or translucent solution when added to water. These fluids contain synthetic water soluble lubricants which give them the necessary lubricating properties. In addition, these synthetic fluids contain rust and corrosion inhibitors, biocides, surfactants and defoamers. Synthetic cutting fluids do not contain any oil. Milanco makes a whole line of water soluble synthetic cutting fluids.

4. Semi-Synthetic Fluids
As the name would imply, the semi-synthetic fluids are a little bit like a synthetic and a little bit like an emulsifiable oil, kind of a combination of the two. These are really synthetic fluids which have a small amount of oil (up to 25%) added to the concentrate. When diluted with water they form a very fine emulsion that looks very much like a solution, but in fact, is an emulsion. The oil is added to improve lubricity. When synthetic fluids were in their early stages lubricity was a big problem, so the semi-synthetics were introduced. However, with the technology in synthetic lubricants improving, lubricity is not the problem it once was for synthetic fluids and, therefore, the semi-synthetic is becoming less popular.

When talking about cutting fluids it is very important that you understand the differences in the four groups.

Water Soluble Cutting and Grinding Coolants

As tool penetrates workpiece, temperature and pressures in the "shear zone" cause plastic deformation at tool tip. A chip is formed which then slides up the face of the tool.

Coolants function to remove heat of internal friction from shear zone; heat of sliding friction from chip/tool interface; and heat of sliding friction between tool/flank and the freshly cut surface.

The coolant must wet, penetrate, and dissipate heat efficiently. It must also create the chemical/lubricating films needed to reduce friction and protect against pressure welding of workpiece fragments to tool surfaces.

Cutting Oils

During the cutting operation, pressures and temperatures are high enough at tool tip for pressure welding to take place. The welding at tool tip is called the BUE (Built-Up Edge) and it dulls the tool. Cutting oils function to minimize or control the BUE by chemical cooling.

Additives such as chlorine, sulfur, phosphorous and fat react at certain temperatures to form and reform adsorbed films which minimize metal-to-metal contact and reduce pressure welding, thus controlling the BUE.

Poor finish is the result of BUE particles breaking off and abrading the freshly cut surface.

How well the cutting oil cools chemically is a function of the product’s chemistry.

Housekeeping Tips

-Choose your coolant carefully. investment in quality saves production dollars.
-Always pre-mix original fill and make-up solution. Don’t guess! Don’t just add water! Pre-mixing gives positive control of dilution and assures uniform performance. Problems of rusting, hardness build-up or bacterial attack are minimized.
-Check concentration regularly. Refractometer checks insure against coolant solutions getting out of control.
-Change and clean machines regularly.
-All coolants perform more efficiently with regular change periods.
-Put clean coolant into an antiseptically clean machine. This lengthens coolant life many times over. Use machine cleaner at every change period. It will save you money!

COOLING TOWERS

Cooling towers are a vital link in a complex system that transfers heat from one point to another. A common use of cooling towers is in air conditioning systems. The air conditioner draws heat from the air in the building and transfers it to water in the cooling tower system. The cooling tower system takes the hot water outside the building, cools it through contact with the air, and then recycles it.

The efficiency of this heat transfer system can be reduced in four ways:

(1) The dissolved chemicals found in most H₂0 supplies can "undissolved" over time and form a hard layer of scale in the system.

(2) Sludqe can accumulate in the bottom of the system.

(3) The continuous passage of the water over the metallic surfaces of the tower system can cause corrosion.

(4) Algae and other organic material can actually grow in the system and foul it.

Why not use water from the city mains, or from a well, for cooling, and then discharge it into the drain? Water conservation is a primary consideration in operating a cooling tower to achieve tremendous savings in water bills and sewerage fees. For example, a 100-ton cooling tower, operating under average conditions, will use only 270 gallons of makeup water per hour, but the same system, operated on the basis of "once through" use of water, would require 18,000 gallons per hour. The difference amounts to almost 6,500,000 gallons per year.

In this continuous recycling of water across the tower, one percent of the circulating water will be lost by evaporation for each 100°F drop in water temperature. Another but lesser amount will be intentionally drained from the system by "bleed-off," a function used to limit the accumulation of solids in the tower water. This evaporative loss and loss of water by bleed-off must be replaced by new makeup water. (Refer to the makeup water gallonage mentioned in the above paragraph).

In the process of evaporation at the tower, only H₂0 is discharged into the atmosphere as water vapor. All the hardness and other dissolved solids of the tower water are left behind. In addition, many varieties of airborne contamination (silt, flue gases, construction dust, etc.) will have been drawn into the system. The scale-forming tendencies and the corrosiveness of the tower water will have increased by these influences.

A major objective of a cooling tower treatment program is to prevent the deposition of hard water scale in small orifices, such as the condenser tubes. Another is prevention of corrosion. Scale and corrosion products constrict the flow of water, reducing the efficiency of the system. In badly neglected systems, pressure builds up in the system to overcome the insulating effect of scale. This will ultimately cause total system failure.

In cooling tower treatment, the water to the tower is fed into the top of the tower. Here, by virtue of evenly spaced orifices in the "distribution pan" the downflow of water is evenly distributed over the entire tower surface. As it falls downward across baffles, the water is broken into small droplets to accelerate the rate of evaporation and cooling. Evaporation is further increased by fans in addition to natural air drafts.

Strange as it may seem to you, the human body provides a very graphic illustration of cooling by evaporation. Here is a cooling system which, during the summer months, maintains the temperature of the body to within several tenths of a degree, regardless of the temperature of the air surrounding the body. It is done simply by cooling through EVAPORATION.

On a warm day when you work or play hard, your body heats up, and you begin to sweat. Because your skin is more moist than the air, the sweat EVAPORATES and it ABSORBS heat from your body. By absorbing heat from your body, the temperature of your body is lowered. It is the evaporation or the change from a liquid to a vapor of the water on your skin which causes the skin to be cooled. If you stand in a breeze, you feel cooler, even though the temperature of the breeze will be the same as the temperature of still air. The breeze STEPS UP the EVAPORATION process of the sweat and more rapidly cools the body. It is not the breeze alone that makes you feel cooler. It is the increase in the rate of evaporation which makes the body feel cooler.

Water used in cooling towers contains dissolved impurities because water is capable of dissolving a wide variety of solids and gases in infinite combinations and amounts. Water, although pure enough to drink, is usually not good enough for use in a cooling tower until it has been treated with scale and corrosion inhibitors.

Among other dissolved solids, water contains calcium and magnesium salts -- commonly referred to as "Hardness." These salts have only limited solubility -- that is, only a certain amount will be soluble in a given volume of water. As a sample of water evaporates, sediment begins to form at the bottom of the container. Only the water evaporates; all the solids stay behind. When sediment starts to form, we have reached the "limit of solubility."

The sediment which forms when the "limit of solubility" is reached causes scale formation. This scale can be very hard and difficult to remove. Scaling in the heat exchanger or compressor serves to insulate the system and reduces the cooling efficiency. Therefore, water must be "conditioned" to prevent this scaleforming tendency.

In addition to dissolved "solids," water usually contains dissolved gases which it picks up from the air. The two most prevalent are oxygen and carbon dioxide. other gases, such as sulfur dioxide or nitrogen oxides from exhaust fumes, can form acids when dissolved in water. These dissolved gases can, in time, completely destroy parts of the tower. Thus, the water must be conditioned to prevent acidic corrosion.

There is another problem with cooling towers that is not encountered in boiler water treatment. This occurs when air is brought into intimate contact with the cooling water as it passes over the cooling tower. Because of pollution, the air contains a wide variety of impurities -- both solids and gases. As it passes through the water in a cooling tower, the air is effectively "scrubbed," and the impurities are transferred to the water. Thus, the dirt picked up from the air along with precipitated Hardness and suspended solids make up the major cooling tower water contaminants. As these solids accumulate in the system water, they must be removed by bleed-off. If they were allowed to continuously concentrate in the cooling system, they would create sludge in critical areas and reduce the ability of the system to cool.

The problem of water impurity is controlled in two ways:

(1) By introduction of chemicals, which prevent the dissolved solids from precipitating as scale...and which prevent corrosion.

(2) By bleed-off, which limits the solids concentration at a level which can be successfully handled by chemical treatment.

Another problem results when the moist surfaces of the tower are exposed to sunlight. This promotes the growth of algae, bacteria and fungal slime. Large masses of slime or algae growth can accumulate rapidly, causing clogging, reduced flow, and reduced heat transfer. This "fouling" must be prevented.

The operating efficiency of a cooling tower system is adversely affected by:

(1) Scaling, which must be controlled chemically and also held in check by bleed-off.

(2) Corrosion, which must be overcome by chemically neutralizing the acidity which has been picked up by air pollution, or which is present in the makeup water.

(3) Organic fouling, which must be brought under control by chemicals with algaecidal properties.

The amount of dissolved solids in the tower water is evaluated in terms of "cycles of concentration." This term is used to describe the ratio of tower water solids to raw water (makeup water) solids. To measure cycles of concentration, the chloride content of the tower water and the chloride content of the raw water are compared as follows:

Cycles of Concentration = tower water chloride
                                              raw water chloride

For example, if the chloride content of the tower water is 120 ppm and the raw water chloride is 40 ppm, the cooling tower system is operating at three (3) cycles of concentration. Chloride is the most accurate titration to use for this purpose because:

(1) Chloride is present in all raw water.

(2) Chloride is the most soluble of the dissolved solids in water, and the last to precipitate; therefore, no other solid will concentrate more. This assures the accuracy of your measurement.

(3) No chloride is used in our treatment compounds, therefore, the titrations are not influenced by the presence of chemical treatment.

To maintain the cooling system water at a specific number of cycles of concentration, a regulated rate of bleed-off of tower water must occur. At three cycles of concentration, bleed-off is one-third of the makeup water volume. At four cycles of concentration, the bleed-off rate is one-fourth the makeup water, etc. The balance of the makeup (not leaving the system via the bleed-off drain) is evaporative loss. The actual rate of evaporation is easily computed. If two of the following factors are known this equation can be completed.

    Bleed = Evaporation + (concentration - 1)

    B = E divided (C-1)

    MakeUp = Evaporation + Bleed or

    MU = E + B

EXAMPLE: Chloride tests have shown three cycles of concentration. Bleed has been measured at the rate of 8 GPM. Therefore:

    B = E divided (C-1)
    B = E divided (3-1)
    8 = E divided 2
    8 = 16 divided 2

and we can say that evaporation is 16 GPM and makeup (E + B) = 24 GPM.

If the rate of evaporation never fluctuated, there would be no need to change the rate of bleed-off. But more water evaporates at 2:00 p.m. on a hot day than at midnight on the same day. All three factors of tower management (evaporation - bleed - makeup) change as the "demand" increases or decreases. Over the entire cooling season or, in fact, during any 24-hour day, the "demand" will average 50% of the rated capacity of the system. At 2:00 p.m. on a hot day, the rate of evaporation, the rate of bleed-off and the rate of makeup may approach the figures shown below for operation of the tower at 100% capacity. During the nighttime, cooler hours of the same day, the "demand" decreases making the average hourly "demand" 50% of the full capacity "demand."

EVAPORATION, BLEED-OFF AND MAKEUP HOURLY RATES
                         FOR THE OPERATION OF A 100-TON

Operation at 100% capacity                       operation at 50% capacity

cycles              2      3      5       7      10          2    3     5     7   10
gph evap.       180  180  180  180  180       90   90     90     90      90
gph bleed       180  90     45    30    20         90   45     22     15      10
gph makeup   360  270  225  210   200     180    135  112   105   100

In the operation of a 100-ton tower at three (3) cycles of concentration, the rate of makeup will averaqe 135 GPH, even though during part of the day the makeup may be as high as 270 GPH. The next page will be devoted to the use of automatic controllers to continuously balance the feed and bleed factors so that wastage is minimized and protection to the system is maximized.

The introduction of chemicals into a cooling tower is performed in a number of ways. The simplest, least effective method is "slug feeding." The operator throws a canful of compound into the tower basin when he thinks about it.

Somewhat more operator attention is given to a "by-pass feeder," another hand-operated batch feeder that is installed in the piping in the equipment room. This eliminates the need to go up to the rooftop tower to apply treatment; however, all of the obvious faults of "slug feeding" still exist.

All such crude methods result in periods of wasteful overdosage followed by longer periods of severe undertreatment. These peaks and valleys have no relationship to the rate at which makeup water enters the system. With hand-feeding methods, the tower may be without protection when the need is greatest. Manual adjustment of the bleed-off also contributes to chemical and water wastage, or it allows excessive sludge to build up in the system.

The Milanco "Feed Pump" overcomes these inadequacies by feeding and bleeding the system once every ten minutes. The following instructions show how the Tower Tender is positioned in the equipment room -- how to set the Timer for towers of from 50 to 240 tons of refrigeration -- how to service the installation and other pertinent details. When these guidelines are followed, the tower will operate within a range of 3 to 5 cycles of concentration. Never less than three -- no more than five.

HOW TO INSTALL THE FEED PUMP
AND TOTAL TOWER IN A COOLING TOWER

THIS INSTALLATION DOES NOT REQUIRE TOWER SHUTDOWN

(1) Move the TOTAL TOWER drum to a location close to the system circulating pump.

(2) With the assistance of the equipment operator, select a TOTAL TOWER injection point on the discharge side of the circulating pump. insert a "T" in the pressure gauge assembly. Do not move the gauge to make this installation until the valve between the water line and the gauge has been securely closed. Connect the plastic tubing to the "T." Replace the pressure gauge, but do not reopen the shutoff valve at this time.

(3) Set the Feed Pump on the drum head, or mount it on the wall about 8 inches above the drum. Connect the siphon tube and insert it into the drum. Connect the discharge tubing from the Tower Tender to the injection fitting. Now, reopen the shutoff valve.

(4) With the assistance of the maintenance man, locate the tower bleed-off assembly. Insert the electric bleed valve, followed by the 4 gpm flow regulator. Wire the electric bleed valve to the Feed Pump. Electrical services should be performed by the electrician, and should conform to local code.

(5) Plug the line cord into a 110 volt outlet. Use electrical service outlet that is energized only when the tower circulating water pumps are operating. You are now ready to add TOTAL TOWER, as needed, to control scale and corrosion and also ready to bleed water from the system, as required, to maintain control over the total solids in the circulating water.

                    1. Initial Charge

To bring the tower water up to operating strength, put in TOTAL TOWER at the rate of 2.5 pints  per 1000 gallons of system water. Estimate 10 gallons per rated ton.
                        EXAMPLE: 300 tons = 3000 gallons = 7.5 pints.

This can be done at the tower basin or a holding tank. Get the operator to help choose the most  convenient location. After two hours of operation, test the tower water for TOTAL TOWER                           content. The reading should be between 240 and 300 ppm.

                    2. Interim Setting for the Feed Pump

To maintain the proper level of TOTAL TOWER in the tower water, set the Feed Pump according  to this chart:

RATED CAPACITY       240          200          150          100          50
of the Tower                   Tons        Tons         Tons        Tons       Tons
TIMER SETTING           5              4                3              2              1

                        Instruct the operator how to run daily tests for TOTAL TOWER level. Furnish a Test Kit and Log                          Sheets to record these readings. Tell him you will return in several days to inspect the Log Sheet                          and make recommendations based on the data recorded.

                    3. Continuous Maintenance Feed Rate

On your first service call, review the Log Sheet. Confirm the figures by personally running the  following tests before making any "fine tuning" adjustments in the Feed Pump.

TOTAL TOWER Titration

Scale and corrosion protection are performed most effectively when the TOTAL TOWER content of the tower water is between 240 and 300 ppm. If your test result is lower than 240 ppm, or over 300 ppm, you may have been given an inaccurate estimate of the tower tonnage. The Feed Pump knob can be moved higher or lower than its present position, according to your new information.

EXAMPLE: If you originally set the knob at Position #2 or a two-ton tower, and your first TOTAL TOWER test shows 180 ppm, the Tower Tender knob should be moved up to between Positions #2 and #3. If a change of setting is indicated, return within a week and repeat the tests for confirmation.

Molybdenum Testing

This is in the treatment as a corrosion inhibitor and is easy to analyze using our instruments. The molybdenum is in the water at the specification level when the treatment level is correct.

4. Teach The Operator To Make Daily Tests

The full cooperation of your customer and his staff is the difference between success and mediocrity. Run through the two tests with these people. Tell them how to enter the results on the Log Sheet. Urge them to phone you for service when the Log shows any deviation from normal. Explain that prompt service at this time will prevent problems in the future.

BOILERS

A boiler is a container in which water is converted to steam
for heating buildings and for any of the many operations that
require heat or steam.

    There are basically two types of boilers:

        A. WATER TUBE (20% of boilers in use)
             Water is fed through a bundle of tubes inside the boiler,
             and heat is applied to the outside of the tubes to heat the water.

        B. FIRE TUBE (80% of boilers in use)
            Heat travels through a bundle of tubes inside the boiler to heat
            the water surrounding the tubes.

The bundle of tubes which carries water in the Water Tube Boiler and
heat in the Fire Tube Boiler is called the Heat Transfer Surface.

Both the Water Tube and the Fire Tube Boiler have the following components:

        HEAT SOURCE - A gas, oil, or coal burner heats the water in the oiler.

        WATER SOURCE - The makeup water entering the boiler from the local
water supply is the water source. It may be preheated (in large systems it is
nearly always preheated) to drive off dissolved oxygen and carbon dioxide
gases before the water enters the boiler. Since these gases dissolve more
readily in cold water, preheating helps to eliminate them. Dissolved gases
cause corrosion in the boiler.

The makeup water is often held in a tank (Condensate Receiver). Here it is
combined with hot condensate. Scale and corrosion prevention chemicals
are added at the receiver to condition the water before it enters the boiler.

         FEED WATER PUMP - When heated water from the boiler is given off
as steam, the pump draws feed water into the boiler from the condensate
receiver. The feed water pump must generate sufficient pressure to overcome
the pressure in the boiler.

        BLOWDOWN VALVE - This valve allows some of the water carrying
accumulated solids ("sludge") in the boiler to drain into the sewer. The act
of removing water and sludge from the boiler is called "blowdown."

        WATER LEVEL CONTROL - The Water Level Control maintains the
proper water level inside the boiler. This water level can be visually checked
at the sight glass,

The boiler tubes will become overheated if the water level is too low to keep
the heat transfer surface covered. Low water level will cause excessive
stress to the boiler. High water level will allow water to get into the steam
lines, reducing the efficiency of the boiler system.

       SAFETY VALVE - This valve automatically releases any excess pressure
that builds up in the boiler. Every boiler has several safety mechanisms that
will shut it off in the event of malfunction.

Natural water can damage a boiler by producing: 1) scale and 2) corrosion.

Water always contains some impurities in the form of dissolved solids and
gases. The solids are calcium, magnesium, and other salts that form scale;
the dissolved oxygen and carbon dioxide gases cause corrosion of metal.

1. SCALE

As water flows over rock formations and through the earth, it picks up and
dissolves calcium and other metallic salts. When water enters a boiler,
where it is heated to produce steam, these dissolved solids precipitate
out of solution. The precipitates are left behind in the boiler water--they do
not travel with the steam. If they are allowed to accumulate, they will settle
out as scale on the boiler metal. This is what happens when water in a pan
on the stove is allowed to boil dry, or when water in a glass is allowed to
evaporate completely. A residue of salts will be left, which is scale. The
amount of scale depends on the amount of dissolved solids in the water.
If water is added, the scale residue will not go back into solution. The U.S.
Bureau of Mines has determined that only 1/9" scale in a boiler increases
fuel bills 16%. When chemical treatment is nor used, scale forms in a boiler.
If scale is allowed to build up, it reduces the heating efficiency of the boiler.
A heavily scaled boiler heats water to steam at a slower rate, because the
scale acts as an insulator. This increases operating costs.

TREATMENT FOR SCALE PREVENTION

Milanco Boilertreat 1000, 1000S, 1000HP and 1000 HPS all prevent scale
formation by causing dissolved solids to precipitate as light, fluffy sediment
which settles to the bottom of the boiler. This sediment will not form a hard
scale, and is easily flushed away in the blowdown.

2. CORROSION

Gases in the air are soluble in water. The two that cause the most problems
are oxygen and carbon dioxide.

Dissolved oxygen in water entering the boiler causes corrosion, which will pit
and weaken the boiler. Rust is formed as a by-product. Rust deposits interfere
with the boiler's heating efficiency. This slower heating ability increases the
boiler's operating cost.

Carbon dioxide corrosion occurs in the condensate return system. Carbon
dioxide is released as a gas when water is converted to steam. This gas
travels with the steam. When steam liquefies and enters the condensate
return lines, the carbon dioxide gas is absorbed in the condensate water,
forming a weak acid which will eventually "groove" or wear away the metal.

CORROSION PREVENTION

Milanco Boilertreat 1000 and Boilertreat 1000 HP contain oxygen scavengers
to inhibit the corrosive action of the dissolved oxygen. Boilertreat 1000 is
recommended for boilers that operate under 75 psig. Boilertreat 1000 HP is
recommended for boilers that operate at pressures between 75 psig and
300 psig.

Boilertreat 1000S and 1000Hps has a neutralizing amine that increases the
pH of the water to an alkaline level, from 7 to 8.2 (explained later). This also
will neutralize the corrosive acid formed by carbon dioxide.

TREATING THE WATER

Natural water is not pure. Rain water is contaminated by airborne dust particles.
Water passing through soil and over rocks picks up minerals. Even mountain
spring water derives its good taste from the minerals it contains. These same
minerals cause scale in boilers--consequently, all boiler feed water requires
treatment.

We said in an earlier part that water contains various impurities in an infinite
variety of combinations and amounts. Water from different locations, then, will
differ in the amount of chemical treatment needed to prevent scaling and
corrosion. We must run tests on the water at each location to determine how
much treatment should be used. The tests we use are as follows: (Detailed
Test Instructions are included in the #1900 Test Kit).

1. HARDNESS TEST - Hardness is a word used to describe dissolved
calcium and magnesium salts in water. We can determine the amount of
these salts in water by simple titration; that is, adding chemical Hardness
indicators to a sample of water.

Hardness is expressed in ppm, which stands for parts per million. Let's say
the result of the Hardness test is 20 ppm. This means that for every 1 million
pounds of water, there are 20 pounds of Hardness salts (dissolved calcium
and magnesium).

Hardness in ppm may be converted to grains per gallon_by dividing the
ppm reading by 17.

                          Hardness ppm = Hardness grains per gallon.
                                    17

Example: Water Hardness of 170 ppm is converted to 10 grains per gallon.

                 170 divided 17 = 10 grains per gallon

Conversely, to convert from grains to ppm, multiply the value in grains by 17.
Hardness grains per gallon x 17 = hardness ppm.

Example: 10 grains = 170 ppm hardness.

Hardness must be precipitated out of water so that scale does not form. When
high alkalinity is present in the water, the Hardness is precipitated as soft
sludge that is held in suspension by either the boilertreat 1000 series of
chemicals until blowdown. When low alkalinity is present in the raw water,
the alkaline builders in these products provide the alkalinity necessary to
precipitate the Hardness as soft sludge. A smaller dosage will be used if
the makeup water is highly alkaline. The amount of alkalinity in the raw
water is determined by the "M" Alkalinity test.

2. "M" ALKALINITY TEST - This is used to determine the Total Alkalinity of
the raw water in ppm. The result of the "M" Alkalinity test is used to determine
how much Boilertreat 1000 to use. Subtract the "M" Alkalinity in ppm from the
Hardness in ppm and divide by 20 to get the dosage of Boilertreat 1000.

            Hardness - "M" Alkalinity = pints of Boilertreat 1000 to use for each
1000 gallons 20 of makeup water.

Example: If Hardness is 140 ppm and "M" Alkalinity is 80 ppm, then H minus
M = 60 ppm divided by 20 = 3 pints of Boilertreat 1000 for 1000 gallons of
makeup water.

3. SULFITE TEST - This test indicates the amount of Sulfite in the water. Sulfite
and oxygen cannot coexist; therefore, by keeping an excess of sulfite in the boiler
water, we can be sure there is no oxygen is present. If no oxygen is present, no
acid can be formed and there will be no corrosion.

4. CONTROL TEST FOR ISOMINE - Phenolphthalein is an indicator which is
colorless below and pink above a pH of 8.2. When the pH of the condensate is
higher than 8.2, pink indicates that corrosion is being prevented effectively. A
red color indicates excess chemical is being used; therefore, the feed rate
should be reduced.

5. CHLORIDE TEST - When water is converted to steam, the dissolved solids
do not travel with the steam, but are left behind in the boiler water. Water enters
the boiler to replace the amount lost through steam evaporation. When this new
water is converted to steam, more solids are left behind. As steam is continually
produced, evaporated, and replaced with new water, the amount of solids in the
boiler continues to increase.

For every pound of steam generated, a pound of water must be replaced. The
amount of solids in the water will have doubled when the amount of new water
that has entered the boiler is equal to the amount of water that was used to
originally fill the boiler. When the amount of solids has doubled, there are 2
cycles of concentration in the water; when the amount of solids has tripled, there
are 3 cycles of concentration. Cycles of concentration is an indicator of the
amount of solids buildup in the water.

Chloride is chosen as the indicator for cycles of concentration because, 1) it is
always present in the makeup water, 2) it does not change character when
heated, 3) it is not affected by chemical treatment, and 4) like the other dissolved
solids, it does not leave the water in the boiler when steam is produced. If the
Chloride in the water doubles, all the solids have doubled.

The Chloride Test is run on a sample of the raw water and on a sample of the
water from the boiler sight glass. When the Chloride reading of the boiler
water is 6 times the Chloride reading of the raw water, there are 6 cycles
of concentration.

To select the "maximum allowable" cycles of concentration, divide the raw
water hardness into 1000.

                         1000                                = 10 Cycles of Concentration
Makeup water Hardness of 100 ppm

Blowdown should occur at 10 Cycles of Concentration or before.
    1000       = Cycles of Concentration
200 ppm H

Blowdown should occur at 5 Cycles of Concentration or before.

The boiler should never be operated over 10 Cycles of Concentration.

At this point, you are ready to learn how to apply the information from earlier
parts to make cost estimates and proposals for customers with large or
small boiler systems using hard or soft water.

1. Selecting the Right Milanco' Product - Since waters in every part of the
country contain some Hardness, you will use Boilertreat 1000 series of
chemicals as the scale prevention product for most boilers. There is no
harm in treating soft water with this Boilertreat 1000 Series chemical.

2. Determining the Dosage Rate of Boilertreat 1000 - Most boiler operators
are accustomed to using water treatment in "pints per 1000 gallons." To figure
the dosage of Boilertreat 1000 in pints per 1000 gallons, use this formula:

Hardness (in ppm) - "M" Alkalinity (in ppm) divided by 20 = dosage in pints/
                                                                                                      1000 gallons

or, to state it more simply: H - M divided by 20 = pints/1000 gallons

Example: Hardness = 190
                 "M" Alkalinity = 130 ppm

                  190 - 130 = 60 divided by 20 = 3 pints/1000 gallons

3. Estimating Gallons of Makeup Water per hour - To use the following chart,
find out from your customer:

            a. The size of the boiler in Horsepower.

            b. The percent of Condensate Return.
                 If you do not know the percent of Condensate Return, use 50%.

To determine gallons of makeup per hour, refer to the line in the chart listing
the Horsepower of your boiler, then refer to the correct % Condensate Return
Column for the amount of gallons.

Example: A 125 HP boiler with 40% Condensate Return will use a maximum
of 300 gallons of makeup water per hour.

GALLONS OF MAKEUP WATER PER HOUR
AS RELATED TO HORSEPOWER AND CONDENSATE RETURN
PERCENT OF CONDENSATE RETURN

If you do not have this chart available, figure the gallons of makeup per hour
using one of the following formulas:

            a. If there is no Condensate Return

           A boiler uses a maximum of 4 gallons of water per hour per Horsepower:
           amount of Horsepower x 4 =    gallons of makeup water per hour                                                                                                                                                                                                                                                                                                                                                                                                       

Example: A 100 HP boiler with no condensate return uses a maximum
                 of 400 gallons of water per hour (100 x 4 = 400).

            b. If there is Condensate Return   

Figure 4 gallons of water per hour per Horsepower, less % of Condensate
Return.  Amount of HP x 4 - % Condensate Return = gal. makeup water
                                                                                            per hour (gph)

Example: A 100 HP boiler with 10% Condensate Return would be 400 gph
less 40 gallons (10%), or 360 gallons per hour, 100 HP x 4 = 400 gph - 40
(10% of 400) = 360 gph.

4. Calculating Price - When estimating the cost of Water Treatment products
for the amount of water you will be treating, follow these two guidelines:

            a. Round off your estimate to the nearest even number when quoting
dosage rate per 1000 gallons of  water.

            b. Recommend "X" number of pints of treatment per 1000 gallons of
makeup water (a pint is equal to a pound), quote cost in price per pound.

To figure price per pound (pint), use this formula:

Hardness in ppm less "M" Alkalinity in ppm divided by 20 = pints per 1000
gallons x price per pound of product = cost per 1000 gallons.

H -"M" divided by 20 = pints/1000 gallons x price/lb. = cost/1000 gallons.

Example: Hardness = 160 ppm; "M" Alkalinity = 70 ppm

       160 - 70 = 90 divided by 20 = 4.5 pints (pounds), rounded off to 5 pints
or 5 pounds x price per pound = cost per 1000 gallons.

To figure cost of treatment per day, use this formula:

Cost per 1000 gallons x gallons makeup water per hour x hours of operation
per day = cost per day.

CONDENSED VERSION

Determining Dosage Rate of ISODEX

Hardness (in ppm) less "M" Alkalinity (in ppm) divided by 20 = Dosage in
pints/1000 gallons.

Estimating Gallons of Makeup water/hour

            (a) No Condensate return
                  Boiler HP x 4 = gallons of makeup water per hour.

            (b) With Condensate return
                  Boiler HP x 4 - percent condensate return = gallons of makeup
water/hour. Multiply either A or B by number of pints of treatment per
1000 gallons of makeup water.

Figuring Cost per 1000 Gallons

Hardness (in ppm) less "M" Alkalinity divided by 20 = pints per 1000 gal.
Pints/1000 gal. x price per pound of Boilertreat 1000 = Cost per 1000 gal.

Cost of Treatment Per Day

Cost per 1000 gallons x gallons of makeup water per hour x hours of
operation per day Cost pet day.

5. Determining the Blowdown Schedule

As you will recall, 1000 divided by Hardness in ppm = maximum cycles
of concentration.

Example: 1000 divided by 180 ppm Hardness = 5 Concentrations.

This figure is the maximum allowable cycles of concentration. This
does not mean that you must or should allow this many cycles. Running
the boiler at this maximum or critical limit may result in more frequent
need for service on your part. Therefore, it may be desirable for you to
run the boiler at 3 cycles instead of 5 as in the example above. This
determination will hinge upon your judgment of the reliability of the boiler
operators in following your recommendations during your absence.

The decision can also be based on the figures revealed by your
competitor's log sheet. If his instructions have been consistently ignored,
your chance of success at maximum allowable concentrations is not good.

6. For example: A boiler is rated at 150 Hp, and you esitmate 20%
Condensate Return. Here’s what you do:

        a. You test the raw makeup water and get the following
            results: Hardness - 140 ppm; "M" Alkalinity - 80 ppm.

        b. You figure the product dosage.
            H - M divided by 20 = pints per 1000 gallons dosage.
            140 ppm - 80 ppm = 60 ppm divided by 20 = 3 pints per 1000 gallons.

        c. Since the water contains Hardness, you choose the product.

        d. Use the chart to determine gallons of makeup water per hour, or figure
it this way:
            150 HP x 4 gal. per HP = 600 gallons per hour, less 120 gals. (20%
Condensate Return) = 480 gallons makeup water per hour.

        e. You determined above that the dosage will be 3 pints per 1000 gallons.
Since the boiler is using 480 gallons per hour, you will be using about 1.5 pints
(1.5 lbs.) of Boilertreat 1000 per hour. The cost per hour of operation will then
be 1.5 lbs. x price per pound (price x 1.5).

        f. You can allow a maximum of 7 cycles of concentration (1000 divided by
140 ppm Hardness = 7), but you would probably do better to operate at 5 cycles.

This is enough information to get the boiler operating properly. See that the
Control Tests are made regularly, and that blowdown is not neglected.

CLOSED SYSTEMS

Previous subjects have directed your attention to steam boiler systems in which
some of the steam is consumed in food preparation, sterilization, steam cleaning
and "process" work. The condensate developed at these points of steam use is
seldom returned to the boiler on a 100% basis. The steam that is intentionally lost
in this manner must be replaced with new makeup water. Previous lessons have
explained how this water exchange continually brings new Hardness into the
system, which, in turn, requires continuous chemical injections.

Heating boilers continually recirculate the same water. Condensate return is
theoretically 100%, but in practice, some small amounts of water are lost by
occasional blowdown and pipe leaks in the system. This is a closed system
because it loses no steam and takes on no new water.

Since new water does not enter the system, there is no concentration of the
scale-forming nature of makeup water. Our treatment program is, therefore,
directed to the prevention of corrosion in the closed system. Use Closed
System CT to apply a protective inhibitor film on the metal surfaces. This film
prevents contact between the metal and the water containing dissolved oxygen,
which, as you have learned, is the source of corrosion. Our concern is to maintain
an adequate level of Closed System CT to preserve this inhibitor film. We have
no need to test the water for Hardness in order to make the product installation.

1. The start-up charge of Closed System CT is slug fed into the top handhole of
the boiler, using enough to bring the Closed System CT content up to the rate of
one gallon to each 250 gallons of water. The capacity of the boiler can be
determined by asking the operator for his estimate, or by multiplying the
rated HP by 10.

Example: 100 HP = 1000 gallons

2. Unless some unforeseen accident occurs, the original chemical level will be
retained indefinitely and will only need additions once or twice a year to
compensate for leaks or other unintentional losses. Constant call-backs,
Service Reports, and other nonproductive customer relationships
are eliminated.

3. Following the original installation, no chemical expertise is needed to make
the additions of chemical that may be required several times each season.
Closed System CT is added through a by-pass feeder which is installed in the
boiler feed water line. The amount of the addition is determined by matching the
boiler water color to a plastic color standard furnished to each Closed
System CT user.

A. Corrosion Inhibitor

    1. add two total tower inhibitor in the estimated starting dosages
    2. check weekly - pH, conductivity, Molybdenum
    3. adjust dosage based on weekly checks
    4. send sample to lab monthly
    5. adjust dosage based on lab results
    6. visually inspect tower quarterly

B. Biological Control

    1. add biocide A or B based on estimated starting dosage
    2. check weekly - visual test and odor
    3. Alternate biocide A and B to prevent resistant strains from developing
    4. send sample to lab monthly
    5. adjust dosage based on lab results
    6. visually inspect tower quarterly

WATER WASH CHEMICALS

Chemical treatment is required in most water wash paint booths. To meet these needs you have the most complete line of products of any chemical supplier. In the following we will take each need one by one, relate which products are applicable and explain the products' action in treating the need.

Paint Kill With Alkaline Treatment Products

The basic need for all water wash booths is for a product to kill the paint (eliminate tackiness) in the solution tank. If the booth does not contain a treatment product, the paint will stick and adhere to the solution tank, the nozzles and eventually clog the circulation system.

One type of paint kill is based on reaction of the paint with an alkaline treatment product. The alkali in the product reacts with acid sites in the paint resin. This usually requires a pH in the solution above 9.0. A bad side effect of this type of kill is that some of the resulting reactant products may be soaps and cause foam. That is why it is best to use only the minimum amount of treatment product necessary to achieve the desired killed condition.

The type of paints that are traditionally treated with these alkaline products are basically the solvent containing, oil based paints.

However, new laws of Federal and State Environmental Protection Agencies are inducing paint companies to put less solvent in paints. Because of these changes the traditional high solvent paints are gradually being eliminated in industrial accounts. They are being replaced with high solids and water borne paints.

The high alkalinity type paint kill is also used on the new high solid paints. However, the alkaline treatment products for high solid paints, have increased wetting properties. This is because the new high solid paints contain less solvent than the traditional paints and need increased wetting for proper treatment.

Paint Kill With Acid Treatment Products

As you just learned, in industry today, most paints are treated by an alkaline treatment product. However, there is another new type of paint coming into use, which can be treated by acid products. This paint is called water borne or water based. Resin systems in these paints are treated at a solution pH of 4 to 6.

Defoaming

The need for defoaming in water wash booths seems to be on the increase. This can be attributed to the gradual switching to the new type paints and to some of the newer type paint booths. The new high solids and water borne paints have the tendency to foam more than traditional paints. Also some of the new paint booths are attempting to achieve better break up of the paint particles with turbulent action in the solution tank.

The other source of foam, is the possible formation of soap resulting from the reaction of an alkaline treatment product with the paint.

It is important to note that foam helps to float paint. If the customer desires to float the paint, eliminating all foam may allow a heavy paint to sink.

In your standard line of treatment products, de-foaming properties have been put into the products. However, it is impossible and too expensive to have enough defoamer in the treatment products to adequately handle all foaming problems.

Excessive foaming in paint booths is best treated by using a separate defoam product in addition to the treatment product. Some standard organic solvents or oils are sometimes added to kill foam. A safer method is to use organic defoamers. These organic defoamers concentrate near the solution surface preventing the formation of foam bubbles.

NEVER USE SILICONES FOR DEFOAMING PAINT BOOTHS. A trace amount of silicone in the atmosphere can cause a serious paint coating problem referred to as "fish eyes". These are small spots over which the paint will not coat and have the appearance of fish eyes.

Paint Treatment With Flocculites

The furthering development of the Milanco Water Treatment Product Line has exhibited that some of the flocculants products in that line, can also effectively be used to aid in treating paint in water wash booths. The flocculant product is not normally used by itself, but is used as an additional product along with the paint kill product.

When a flocculant is used at low concentrations up to 50ppm, it will cause the killed paint particles to floc together. This helps to better separate the killed paint from the water and makes it easier to collect the killed paint. Dewatering of the paint is faster, thereby reducing the quantity of waste paint solids generated.

For heavy paints, flocculation into larger particles may cause the paint to sink, if this is desirable.

When a flocculant is used at higher concentrations, 300 to 1000 ppm, it reacts just the opposite as it did at low concentrations, and now causes the killed paint to defloc and break up into smaller particles. Killed paints that would normally sink, can be suspended longer with this defloccing treatment. This provides extended time and surface for the paint booth compound to kill the paint. This results in a more efficient use of the booth compound and an overall cleaner system.

However, not all killed paints are susceptible to flocculant treatment. This can be pre-tested with a flocculant test kit or by sending a paint sample to the Milanco for testing.

Floating Overspray

Paint overspray is normally heavier than water and thus has a strong tendency to sink. One action that helps to float the paint in some booths, is the churning action of the water. This causes air to be entrapped, thus suspending the killed paint. Foam also helps to float paint. Another method, if the paint is susceptible, is defloccing the killed paint into smaller particles with a flocculant.

With time most paints will eventually sink. Floating sludge should be removed at a rate which disallows sinking. The weight of the paint and how long booth conditions and treatment products can float it, will dictate if surface skimming is the optimum method of removal. The alternative is allowing the paint to sink and eventually removing the sludge from the tank bottom.

Sinking The Overspray

Surface skimming is the usual preferred method of paint removal, but there are times when a customer desires to sink the paint. To accelerate sinking If the paint is susceptible, floc the killed paint with a flocculate. This also achieves a more de-watered sludge. With some paints, an over-kill with higher concentrations of booth compound, may accelerate sinking.

There are two programs that promote the sinking of paint solids. The first actually detackifies the paint particles and keeps then in suspension. A centrifuge or hydrocyclone is then used to continually remove the solids from the booth water. The water is then returned to the booth with the unused detackifier, still active and ready to treat more paint overspray. These machines will only remove the paint particles that are heavier than water and big enough to see. The paint detackification program is very important to maintain because the paint particles may pass through the pump, manifold, risers, and spray nozzles many times before being removed by the centrifuge or hydrcyclone.

The second program is to simply allow the paint particles to sink to the bottom of the booth. The tank is drained periodically and shoveled out by hand, or periodically vacuumed out with an industrial paint solids vacuum that filters out the solids and returns the liquid back to the tank. The paint detackifier must keep the paint solids from sticking together so that the sludge on the bottom does not turn into a layer of "putty."

Paint which is allowed to sink can be removed in several ways. A centrifuge or hydrocyclone is used when the water is kept in constant motion and the paint particles aren’t heavy enough to stay on the bottom when the recirculation system is turned back on.

Booth Rust Preventation

Rust is prevented in two ways. If the alkalinity of the solution is kept at a pH of 9 or more, there is little chance of rusting. For those treatment compounds which work at a pH lower than 9, chemical rust inhibitors are used in the products.

Prevention of Micro-Organism Growth

Micro-organisms generally will not grow in environments of greater than pH 9.5. For solutions at pH below 9.5, a well maintained, clean booth with no blockage in the circulation system, will prevent micro-organisms growth. Chemicals which prevent micro-organisms growth are used in your booth compounds. However, there may be extreme conditions when a non-cleaned booth builds up stagnant material and causes a rotten egg odor.

Choosing The Treatment Products

Now that you have some idea of what type of products are used to treat the needs of a water wash solution, how do you decide which of the products to use?

The best answer to this is, have the Milanco Technical Service lab test the paint and tell you what products perform the best. This is done by sending in a quart sample of paint with a work order.

Besides water wash products, Milanco also has a complete line of Paint Booth Maskants. You can sell these for use on any type of booth and almost all paint booth customers use them.

INTRODUCTION

This course is designed to provide information with regard to exterior truck washing. It will help you identify your prospects, make product recommendations, and provide helpful information for selling and applying truck wash products.

CHEMICAL APPLICATIONS

Today appearance maintenance is of increasing concern to anyone who has a fleet. Years ago it made little difference what a truck looked like on the highway. Its job was to get there and back with whatever load it might be carrying. But that was before the days of consumerism, ecology and advertising.

In the course of cleaning the exteriors of trucks and other vehicles, you will encounter various kinds and degrees of soils to be removed. The type of soil will depend on how much the vehicle is in service and on the locality where it is in operation. For example, the cleaning of a concrete truck presents quite a different problem than the cleaning of a milk truck.

Furthermore, you must consider on which surfaces various cleaning compounds are safe to be used. Very strong alkaline products while performing an excellent cleaning job will tend to attack body finishes after only a few applications. Likewise, weaker chemicals may not do an adequate cleaning job and may require scrubbing. Still other cleaning compounds if not rinsed properly will give a streaky, unsatisfactory cleaning job. The point is this - there are cleaning compounds available for almost every kind of cleaning job, and with regular and intelligent use, our chemicals can provide clean vehicles at an economical cost.

There are basically three soil areas of exterior cleaning that you will encounter:

    1. The removal of road film, dust and dirt from the average vehicle.

    2. The removal of grease, oil and encrusted dirt that accumulates on wheels, fifth wheels, undercarriages, etc.

    3. The cleaning of specialized vehicles that transport such loads as concrete, lime, etc.

In all cases, consideration must be given to the soil to be removed and the surface to be cleaned. Never use a product without considering these two factors. While soil removal is the objective, you want to avoid damaging the surface of the vehicle. Also, you'll usually find that one cleaning compound will not effectively clean a total vehicle. In most cases, two or more cleaning compounds will be needed to do the job.

The simplest cleaning problem you will encounter will be the removal of road film, soil and dust from the average vehicle like buses, package delivery vans, and truck cabs. These vehicles come in a variety of sizes with a variety of surfaces to be cleaned. The two most common surfaces you will encounter are painted and aluminum.

At this point you will have to find out from your prospect either by observation or by conversation what type of equipment he has for washing. Most shops have some type of pressure washing equipment; for example, a Graco 10:1 or 5:1 or electric powered centrifugal pump. If they don't, here is your opportunity to change them over from the "brush and plenty of elbow grease technique" to a more efficient operation. Once you know what equipment is available you can select the best product to do the job at the best using cost.

For cleaning the average truck or vehicle, the best cleaners are those detergents having wetting and emulsifying properties for speeding up the removal of the soil encountered. Infrequently washed vehicles with considerable soil build up on them will usually require some combination of concentrated cleaning solution, heat, dwell time and brush agitation for the best results.

From an appearance standpoint light colored vehicles will have to be cleaned more frequently than dark colored ones since dirt shows up more conspicuously on them. In fact, it is becoming a growing practice of many fleet operators to wash their vehicles after each run or at the end of each day. I'm sure no one has to tell you what this practice will do to your income especially if the operator is washing a hundred plus vehicles each day. With more frequent washings, vehicles will accumulate less soil build up. The results will be a situation where operators can change over to less concentrated - less expensive cleaning solutions than those used for infrequently washed vehicles.

GENERAL TRUCK WASHING

The most common cleaning problem involves the cleaning of painted surfaces. These will take the form of over-the-road tractors, route trucks and package delivery vans to name a few. You have a full line of general light duty vehicle cleaners at your disposal for this type of job. None of the products should be applied at temperatures above 160°F and a thorough rinse should be provided. If a white film remains on a vehicle after it has been rinsed and dried there is a good possibility that one or more of the following situations existed:

    1) A thorough rinse was not provided.
    2) Either the surface of the vehicle was very hot or the temperature of the detergent solution was too hot and            resulted in premature drying.
    3) Excessive product concentrations were used.

TRAILER CLEANING:

The hardest cleaning problem involves the cleaning of prepainted aluminum trailers and fiberglass reinforced (FRP) trailers. There are two very effective methods that can be used. The first involves using a high alkaline cleaner like TW 90 or TL-2, brushing it and then rinsing. The brushing step is necessary for breaking the surface bond of the soils. The second method is a "shock treatment" which, while expensive, will do an excellent job. The "shock treatment" consists of applying an acid product such as TL-1 to the vehicle and then immediately following it with an alkaline application without rinsing in between. KJP-230 will work in some situations for the alkaline application; however, TL-2 is formulated for transportation cleaning and will generally do a superior job. T20 Aluminum brightener can be used as an alternative acid product, but it is not as effective. When using the "shock treatment" both products should be used at approximately 1:30 concentration. HF (hydrofluoric) acid and alkaline products cause a chemical reaction which results in the loosening of the soil. CAUTION! Care must be taken when using this method. Be sure to apply the alkaline material first to glass and chrome areas as protection from acid etch which can occur from a acid overspray when cleaning a trailer. Finally, be sure to give the vehicle a thorough rinse.

Aluminum trailers present yet another problem. Here the object is not only to clean the vehicle, but also to brighten its surface. This can be done with either acid or alkaline brightener. Both kinds of brightener cause an etch in their cleaning process. Acid brightener produce a brighter finish job than do alkaline brightener and cannot be expected to perform equally. Milanco acid brighteners, M.A.B. and T-20 and the alkaline brightner, TL-2, will produce surfaces that are bright and free of corrosion. Brighteners are not just raw materials like some that are on the market. They contain inhibitors that allow them to act on dirt and soil without harshly affecting the aluminum surfaces. Don't misinterpret this, though! All brighteners will slightly attack the aluminum surface -- they act by removing the top layer of aluminum oxide which forms when aluminum is subjected to the environment. When this layer of aluminum oxide is removed, a bright, shiny aluminum surface remains. However, remember not to be disappointed when using an alkaline brightener. The finish job will be less dramatic than an acid job. The alkaline brightener is useful in areas where EPA restrictions prohibit the disposal of acids in the sewerage system.

The application of T-20 Aluminum Brightener requires some caution not only because they are highly acidic and alkaline products, but also because if misapplied can cause unsightly streaking. These products should be applied from the bottom-up, never from the top-down, in order to avoid streaking. After a short period of dwell time (never let these products dry on the trailer) follow with a thorough rinse in the same manner (from the bottom-up). In the case of M.A.B. or T-20 rinsing can take place after the product begins its etching action which is visible by a foaming reaction on the surface. Normal using concentrations will vary with these products and with temperatures. These products should be used in the range of 1:10 to 1:40 depending on the condition of the trailer. Keep in mind when heating these products that their chemical reaction will approximately double with every 50°F rise in temperature. This, however, does not mean that the cleaning ability doubles, but only increases, with a rise in temperature. Other variables like concentration, dwell time and agitation also play a part.

In some fleets, you will find aluminum trailers which have unsightly black areas on the front top corner(s). This is caused by an accumulation of diesel smut coming from the exhaust stack of the diesel tractor. TW-90 and TL-2 will eventually remove this, but only after repeated treatments. If your prospect or account should want to remove it fast, apply TL-2 at 1:25 through a pressure washer. Heat will aid the cleaning process since you are essentially removing a carbon soil. This soil will roll off of an aluminum trailer but brush agitation will most likely be required on an aluminum prepainted trailer. Again, be sure to start from the bottom-up to avoid streaks. Also, make sure that no painted signs or decals are near the area where you are working on the trailer -- these products could cause some discoloration or fading of the paint. This application must be immediately followed by a thorough rinse.

Do not attempt to do too large of an area. Remember these cautions when working with our aluminum trailer cleaners/brighteners:

    1) Avoid streaks by applying trailer cleaning products from the bottom-up.

    2) Immediately follow all applications with a thorough rinse starting from the bottom-up.

    3) Do not allow M.A.B. or T-20 to dry on glass -- it will cause a permanent etch.

    4) Do no t use M.A.B. or T-20 on anodized aluminum --it will cause a milky appearance that will have to be            hand buffed.

    5 ) Do not use TL-2 on or near painted signs or decals -- they may cause bleeding. Pretest a small area to            determine safety.

    6) Clean only small areas of the trailer at a time to avoid drying of the chemical on the surface, i.e. work no            more than 10' - 20’ sections at a time.

REFRIGERATED TRAILER CLEANING

Some common carriers and practically all food carriers have specialized temperature controlled trailers for hauling products such as meat, perishable food, and certain liquids which are susceptible to freezing. As a result these units are heavily insulated around floors, sides, and doors. Smooth fiberglass sections or aluminum are used on the inside walls and ceilings, and usually the floors are made out of rigid aluminum. In this case where foods are hauled, these trailers must be cleaned to meet rigid U.S.D.A. restrictions, and the cleaning material must be approved by the U.S.D.A. Most of these carriers clean the inside of these trailers with either a steam cleaner, high pressure hot water washer, or one of these combinations with foam. We have various U.S.D.A. approved liquids and powders which can be used to clean these units. Consult the factory for the correct cleaner for your application.

PREVENTIVE MAINTENANCE (P.M.) CLEANING

Mechanics don't like to work in dirt and grease. Good shop foremen will not want them to work under these conditions because it slows them down and costs extra money in the long run in terms of downtime, equipment road failures, corrosion and labor. For example, a mechanic will spend at least an hour and a half each day cleaning up before maintenance procedures can be undertaken. These kinds of expenses, if excessive, can literally put a trucking company out of business.

Preventive maintenance cleaning means cleaning a vehicle to prepare it for a preventive maintenance check. This entails cleaning the entire power unit which consists of the engine, transmission, greasy fifth wheel, wheels and wheel wells, and chassis. Most fleet maintenance centers have steam cleaners or hot/cold pressure washers for this task. This kind of equipment as well as foam and central cleaning systems are very useful in any P.M. program.

If a company is not using a pre-soak of some type, here is where you can really cut time by selling either a solvent degreaser system or a foam detergent system. The solvent degreaser system is most useful on areas of great grease accumulation such as engines and fifth wheels. EC-320 cleaner in a universal sprayer will penetrate grease and oil fast and loosen it so that it can be flushed down. Spray this mixture on dirty greasy areas, allow a short dwell time (5 minutes) and rinse using a pressure washer or steam cleaner.

The foam detergent system may be preferable to the solvent degreaser system for most applications. However, it cannot be expected to replace it where there are heavy accumulations of grease and oil as may be found on fifth wheels or around lubrication fittings. Foam cleaning is a useful means of producing and applying a stable detergent foam onto the vehicle or wherever soaking action is desired. It is ideal for fleet maintenance programs where tractors are cleaned prior to inspection. Unlike the solvent degreaser system, it can be applied to painted surfaces for total tractor cleaning. A quart of concentrate detergent like TL-2 mixed at 1:10 is sufficient to completely foam down a tractor. This should be followed by an application of one half gallon of the same concentrate mixed at 1:50 through a steam cleaner or pressure washer to wash away the soil held in suspension by the foam. A final clear water rinse will make the tractor ready for inspection. Here are some of the reasons maintenance personnel will like working with foam:

    1) There is little splash back when the foam system is used. This makes the cleaning operation safer, more     economical and more pleasant than other systems used by personnel.

    2) A foam generating wand saves on the use of cleaning solutions by creating a thick lather which clings to      the vehicle. There is no detergent waste and it is less costly than solvent systems.

    3) Regular cleaning of tractors before preventive maintenance checks will remove caked on grease and dirt     making it possible for mechanics to spot effects faster and make repairs easier -- downtime is reduced!

    4) Foam cleaning helps improve the morale of maintenance personnel. It is fun and easy to use, and the           results of foam cleaning give personnel a sense of pride and accomplishment.

The methods just described are not essential to preventive maintenance cleaning but they offer cost and time saving advantages. Steam cleaning or pressure washing normally do the job. Steam cleaning is excellent where high temperatures are needed to melt down heavy grease and oil films. Steam cleaners depend on steam for their working pressures and have a practical operating rate of 60 - 100 p.s.i. at 300°F. However, steam vapors inhibit vision for cleaning especially in cool weather. Pressure washers like steam cleaners use pressure for scrubbing power but they are less costly to operate in terms of energy. Pressure washers cannot generate as much heat (controlled at 210°F or less on hot models) but can generate more pressure (generally 300 p.s.i. to 2000 p.s.i.) for faster cleaning and larger volume jobs. Pressure washers work very effectively when their cleaning nozzles are held 6' to 12" from the cleaning surface in order to take advantage of the spray's cutting edge.

Central cleaning systems which can combine one or more of the methods previously described provide maintenance crews with even greater flexibility. With this type of system power, heat and pumping facilities are in a central location. Then as many cleaning stations as necessary can be strategically positioned inside and outside the shop. The advantages of a central system include: multiple cleaning stations, elimination of several cumbersome machines, higher safety and sanitary conditions, and minimized operator handling.

There are four degrees of steam or pressure cleaning, depending on the job, and the amount of soil: light to medium duty, heavy duty, extra heavy duty and solventized cleaner needs.

SUMMARY

Every company operating a fleet of vehicles whether it be a truckline, busline, concrete company or other operator of a fleet of vehicles has the potential need to clean their vehicles. In doing so, the fleets can be washed either automatically or by utilizing labor. An inexpensive cleaner may provide satisfactory results for your conditions. If not, there are special purpose transportation cleaners built to do the job.

Background

The chemical industry touches every facet of American life: from housing, transportation and health to agriculture, industrial development and economic security. Because of their versatility, tank trucks have played an important role in making chemicals available everywhere. The commodities they haul very often represent a great deal of money to all the companies involved in the shipment.

First of all there is the manufacturer who after considerable investment in research, development, marketing and manufacturing must see that their product is delivered exactly as it was represented during the sale. Then there is the customer who has expensed time and money to set up his production lines to handle the product when it arrives. If the load arrives in a contaminated state, the tank truck operator faces considerable expense in terms of high insurance claims and nonrevenue operating cost for the drivers, tank trucks, dispatchers, tank cleaners and in effect, his entire organization.

With the present cost of equipment and labor, it is necessary for the operator to get as much use from his equipment and road time as possible, which means back hauling whenever possible. Without proper cleaning facilities on both ends of a routing, he is apt to unload in one city and deadhead the tank truck and driven several hundred miles before it begins to earn revenue again. These are some of the reasons why tanks need to be cleaned thoroughly the first time.

Basic Cleaning Methods

Interior tank truck cleaning is often considered to be a complicated procedure, but in essence the procedure is not much different than washing dishes, cleaning carburetors or other metal parts. Knowing exactly how a spinner or spray ball works, the chemical cleans, why heat is used, or for that matter, what is really happening inside the tank will help you overcome many of the difficult problems often encountered.

Interior tank truck cleaning evolved from the principles of immersion tank cleaning. First there are cold immersion tanks which hold cleaning solutions into which parts are dipped and permitted to soak until the soil is chemically loosened for final flushing with water. Recirculation or agitation features were later added to speed up the cleaning time. Agitation of the part or recirculation of the chemical brings fresh strong chemical into contact with the soil and gives mild flushing action at the same time which helps remove the loosened outer layer of soil. This permits deeper penetration of the chemical into the soil until the metal surface itself is reached. Cleaning time was further accelerated by the addition of heat which helps break down certain soils and serves to activate the cleaning chemical. Then impingement from spray jets was incorporated and spray washers were born. Hot impinging sprays coat the parts to be cleaned, provide penetrating agitation and flush the soil away in one continuous process. Obviously a tank truck cannot be placed in an immersion tank or a spray washer, but the principle is the same. Instead spray applicators are placed into the tank truck to accomplish cleaning.

Depending on the soil in the tank truck, cleaning can take one or more of several forms: steam only, heat or cold water only, or any one of these methods with a cleaning compounds added. in almost all cases the spray applicator will simply be one or more spray balls, discs or a high pressure spinner system.

Spray Ball Applicator

The spray ball applicator is a simple ball 2½" in diameter with small holes in it to create a spray pattern. A variety of spray balls with different spray patterns are available depending on the application. The most common type of spray ball available is the Vibra-Jet. These are designed to pass through the standard three inch clean-out opening(s) in the top of the tank.

The spray ball is placed approximately three feet into the tank truck from the top and hot chemical solution is sprayed through it which duplicates the agitated immersion tank or spray washer cleaning effect. The properly designed spray ball for tank truck cleaning will only have holes in the upper sphere of the spray ball to direct low pressure impinging streams of hot chemical to the top of the tank where they can cascade down the sides of the tank. The cascading downward action covers the entire interior tank surface and flushes away the soil as it is loosened by the hot chemical.

Spray balls, properly placed, will give infinite coverage of every single square inch of the tank's interior within five seconds after the supply pump is placed into operation. The area of coverage of one spray ball, placed three feet from the top of the tank, is six feet in all directions. Thus, each ball will cover a 12 foot section of the tank. Multiple compartment and baffled tanks can be cleaned in one operation, as long as there are enough clean-out openings along the top of the tank to handle the number of spray balls needed for complete coverage.

One important thing that must be noted is the whipping, vibrating action of the Vibra-Jet streams. You do not get the same action as a bathroom shower head. The solution flowing into the ball at approximately 25 pounds pressure, creates a strong turbulence that constantly changes the needle-like streams spray pattern, which assures infinite coverage with impingement. This whipping, vibrating action, when witnessed in the open, makes the ball look as if it is spinning, yet there are no moving parts to wear or give maintenance problems. Spray balls are effective on Bunker C, black oil, Bunker #6, etc.

Spray Disc Applicator

The spray disc applicator is a rotating device designed to distribute a dense spray giving a complete 360° coverage of all internal surfaces of a tank. Self operated by the cleaning fluid, the unit revolves in a slow controlled manner so providing quick and effective coverage of the tank interior. Depending on the type of disc, flow and pressure the spray disc can cover from 5’ - 22’ in all directions. The most common type of disc applicator is the Fury Turbodisc. It can be used instead of spray ball applications in 3" clean-out ports and offers these advantages:

- no small holes to get blocked
- lower water consumption - being rotational the disc applicators does not have to cover the whole tank at once
- no need for hole patterns drilled to suit the job

Spinner Applicator

The spray ball or disc type applicator is not the only, or always the best, style applicator to use. Where the spray ball or disc principle of operation is one of low pressure-hiqh volume, units such as the spinners, operate on the principle of high pressure-low volume. On clean bore tanks, these systems are especially effective since they are capable of cleaning the full length of a tank from a central position. on those tank trucks void of clean-out openings, the spinner system is a must, since the centrally located manhole is the only accessible opening to place the spray applicator.

This type of unit, employing two or four large nozzles, rotates on an axis that gives 360° coverage. The cleaning effect is much the same as can be accomplished if two men went into a tank with two fire-fighting nozzles. The entire unit is geared to give a definite pre-determined spray pattern and the speed is always controlled to prevent its operating so fast it would skip sections of the tank.

The driving force of this particular unit is the flow of the cleaning solution forced through it by the application pump's pressure. The pattern of operation is controlled by the pressure generated. Depending on the type of spinner used a liquid pressure of 20 psi or more will drive the spinner. In simple terms, the more gpm that passes through the spinner, the faster it will operate and clean, and vice versa. It should be noted here, generally speaking, the slower this type unit turns for a given nozzle pressure, the better the cleaning. It has an advantage over many other type applicators because of the high pressure chiseling action of the streams. However, rinsing can sometimes be slightly less effective than spray ball or disc cleaning, since the streams themselves tend to have limited coverage. Therefore, a burst rinse operation should be used on final rinsing. Burst rinsing is accomplished by stopping the pump and permitting a complete drainoff of solution, restarting the pump for 5 second intervals and again permitting drain-off, until perfectly clear water runs from the tank. Burst rinsing is effective for working such non-soluble soils as oil, grease, tallow, etc. down the sides of the tank and out the drain. Fury, Orbijet, Sellers, Butterworth, Hydrolance, Gamajet, Wellcojet, etc. are all common spinners to be found in the industry.

Pump and Hose Cleaning

The simple installation of valved pipe nipples to the solution tank permits the direct hookup of the pump to the solution tank and is the surest way to clean pumps and hose interiors. The operation of the pump automatically recirculates the cleaning solution through all parts of the pump and the hoses. This operation can be performed even while interior tank cleaning facilities are being operated.

Where both interior and exterior cleaning of hoses are required, several methods can be used. There is a simple device made from a 20 foot section of 12 inch flanged pipe. This pipe is mounted on the wall with piping running to one end from the solution tank, and piping running from the other end back to the solution tank. One end of the flanged pipe is permanently covered and the other end has a cover that can be easily removed.

Hoses are inserted into the tube and the end plate is locked closed. By starting the application pump, solution is pumped into the tube, passes through and around the hoses to the other end, where the return pump returns it to the solution tank. Rinsing is generally done manually.

More elaborate systems are built, consisting of a large open trough equipped with its own pumping system. The entire trough is filled with the desired cleaning solution and the pumps recirculate the solution from one end to the other. The hoses after cleaning, are removed and layed on a drain trough, and later rinsed with clear water.

Another method is to use an electric drill with a long shaft, equipped at one end with a heavy fibre or wire brush. The entire interior of the hose is reamed out during cleaning, but this method is seldom recommended. It does the job, but the hose life is reduced appreciably.

Recirculation Systems

Spray ball, disc or spinner systems can only be used economically by recirculating the cleaning solution. A recirculation system can be as simple as a self contained system or very elaborate incorporating the use of pumps, tanks and heaters.

The self contained system is only capable of working where spray ball applicators will do the job. This type of system consists of placing a spray ball and approximately 100 gallons of cleaning solution into the tank truck. The unloading line is then connected to the power take off (PTO) pump or Putt-Putt, whichever is available, and the discharge and is connected to the spray ball probe. Another line should be connected between the intake side of the PTO and the tank truck's drain valve to complete the system. Steam can be added for heat if necessary. Two spray balls can generally be used simultaneously with a single PTO. After cleaning, the solution can be pumped off to drums or a suitable holding tank for reuse or disposal. Rinsing can be accomplished by feeding fresh water from a fire hydrant to the pump's intake. Rinse water should be permitted to run to the drain and should not be recirculated. PTO pumps cannot operate spray discs or spinners.

A more elaborate system consists of a solution holding tank, supply pump to operate a spray ball(s), disc(s) or spinner, and return pump for recirculating the solution back to the holding tank. Additional tanks can be added to hold pre-rinse water; additional chemical solutions, such as strong alkalines for stainless steel tanks and inhibited type cleaners for aluminum tankers. Final rinse tanks are more often added as a reservoir for hot water. Heating systems, hose washers and catwalks with drop platforms may also be a part of the system.

Solution Tank Design

Heavy deposits in a recirculation system can clog spray applications, valves and piping. In-line strainers and/or baffled tanks are often used to separate out contaminates from the cleaning solution. The system must be periodically shut down so that the strainers can be cleaned out. Inline strainers can be located on the inlet side of the return pump.

All contaminates fall into three basic categories, the first of which are settleable solids which will sink to the bottom of the tank. The second is floating solids which will rise to the top of the tank. The third is suspended solids which remain suspended in the solution, and cannot be easily removed and cannot do damage through clogging of the system. By placing detention baffles in the line of flow in the solution tank settleable solids can be dropped to the bottom and floating solids raised to the top. As the solution life is used up, the tank is drained and flushed, thus ridding the system of bottom settlings. The floating material can be skimmed off as necessary.

Foaming Problems

Due to the nature of many chemical cleaners, especially when contaminated with other chemicals picked up during the cleaning process, foam can accumulate rapidly, both in the tank truck and the solution tank. Certain steps can be taken to either avoid this completely, or at least retard the foaming action. Since foam is simply air bubbles, the elimination of air will stop foaming, and cutting down on air entrainment into the solution flow will drastically retard its reaccumulation. The most important step in eliminating air entrainment is to balance the gpm output of the application pump with the gpm intake of the return pump. If the return pump is operating at a gpm capacity that is greater than the application pump's output, it will drain the tank truck quickly, thus whirlpooling the solution and eventually draw big gulps of air into the return line. When this air reaches the pump, it will whip the solution into a froth and can easily cause a vapor lock which can damage the pump. Most of this foam will be pumped into the solution tank.

By the same token, if the application pump puts out more gpm than the return pump can handle, a ponding will occur inside the tank truck. As the applicator's streams or rundown hits this pond of chemical, it can easily whip it into a heavy foam condition.

Pumps should be purchased as close to the same gpm rating as possible, and globe valves installed in the discharge side of each pump. These valves can be used to throttle the flow until the system is balanced. ONCE THE SYSTEM IS IN BALANCE, THE VALVE HANDLES SHOULD BE REMOVED TO ELIMINATE FUTURE TAMPERING.

Another source of air entrainment is where the return line feeds into the solution tank. If this enters the tank above the solution level, it will splash heavily into the tank, creating turbulence, which adds more air to the solution. Instead the return line should enter below the solution level to cut down on turbulence.

A foam depressant can be used for knocking down the foam, but foam depressants are not always effective. Its chances of success are better if the previous steps have been taken.

Chemical Cleaners

The above has emphasized the importance of the mechanical systems for cleaning. Yet these systems are merely the methods of applying the most important element of all, the cleaning agent. No system can clean tanks without the proper chemical, therefore, the selection of the chemical cleaner should be done with care. An error in testing and analyzing this part of the cleaning phase could cost manhours, money and can sometimes ruin a complete tank truck.

It is the chemicals' job to dissolve, disperse, loosen, melt, emulsify, or digest the soils to be cleaned from the tank's interior. It is chemically impossible for one cleaner to solve all problems. Everyday of the week researchers are working on paints that nothing can remove, and everyday we are given the task to furnish a chemical that will remove them anyway. So far, to the best of our knowledge, they have been successful only three times; with latex, sulphur, and a Polymer Resin. And we have latex and the resin on the run.

In the selection of chemical cleaners, the wise chemical salesman will make no recommendations, promises, claims or sales until he has thoroughly surveyed the tank truck operator's problems. The following method of surveying the job should not only be expected by the operator, but insisted upon by the sales representative.

1. Determine the capabilities of the mechanical system for cleaning.

2. Supply sample bottles to the customer, labeled, for gathering individual samples of the product that have proved difficult to remove.

3. Determine what metals, such as aluminum, steel, stainless steel, or artificially lined tanks are used for shipping these products.

4. Submit these samples to the laboratory for analysis. These samples can be applied to panels of similar metals. Cleaning agents can then be tested for their effectiveness.

5. Obtain a full written recommendation from the laboratory with concentration, temperature, safety factors and other pertinent data.

6. Take the time and effort to judge the recommendations carefully and follow the laboratory's suggestions whenever possible.

7. Forget the price per pound and base the purchase upon the number of tanks that can be cleaned per pound of chemical, without overlooking the better results, manpower savings, speed of cleaning, and safety of equipment and personnel.

8. Remember that Government agencies do not protect the operator from fly-by- night suppliers that would sell anything to make a buck.

9. Once a manufacturer has been decided upon; a product has been recommended and selected; give a full operational run and expect only the best, and above all, only the possible results.

Some of the more difficult cleaning problems you can expect to encounter are the removal of alkyd resins, acetate resin, acrylic acid, acrylics, adhesive, butylisocyanate, butyl acrylate, contamined PVA, caprolactam, DER resins, dectyl octyl methacrylate, ethyl acrylate, epon NOI, epon resins, flat lacquer, flexon, glacial acrylic acid, glue and liquid glue, lacquer sealer, lacquer, latex, methyl methacrylate, monomer, plastic material, plastic pellets, plastic resin, plastic synthetic, plastic material pellets, paint emulsion, polyether resin, polyethylene, reliance varnish, resin and liquid resin, mixed resins, spent lactum, stryene monomer, synthetic latex, synthetic resin and plastic synthetic resin, wet strings resins and waste chemicals. These and other hard to remove materials can generally be cleaned by one of the following methods. The method to use, again, can be determined by submitting samples to the Transportation Laboratory for testing.

The simplest method calls for using a caustic detergent at 180°F followed by a 180°F rinse and blow or air drying. Many shippers use a flake caustic for cleaning; however, a caustic compounded with wetters and emulsifiers is more effective, rinses better, lasts longer and does not cost much more to use. Clean Out between 8 - 16 oz. per gallon is an effective product to use. It can be beefed up for tougher jobs by the addition of Activate at the rate of 10 lbs. for every 100 lbs. alkaline powder used. Broco 5200W can be used in place of Clean Out for less demanding applications. In order to hold cleaning cost down make up solutions can be handled by adding a mix of Broco 5200W and Activate at the rate of 100 lbs. to 10 lbs. to the solution tank until the desired pH level is attained.

For harder to clean jobs a presolve method is often employed. The presolve method incorporates the use of a strong solventized chemical to penetrate and loosen the product to a point where it can go through the above cleaning process. Milanco has not developed a product for this application because the process is not always effective and it is very expensive. The truck is tied up longer and a good deal of chemical is used. These chemicals generally must run to waste rather than be recirculated since the active life of the solvent is short. After the presolve is rinsed from the tank the caustic wash process can begin.

A third cleaning method literally eliminates the presolve and can be used with most cleaning procedures. This method, a compounded caustic cleaner used with a solvent additive, eliminates downtime involved with using presolve procedures and gets the tanker through the turnaround period faster. This method requires using either Broco 5200W at concentrations of 6 oz. to 10 oz. per gallon with Rinse Aid LF added at the rate of 2.5 oz. per gallon. It has been further established that the addition of Rinse aid LF provides positive foam reduction during cleaning. Do not be turned off by the high price of the solvent additive; its benefits including low use concentrations far outweigh other options. Price objections should be handled by totaling up the cost of current cleaning methods used. Consider, for example, that over 95% of the cost is represented by labor, equipment, steam, water, electricity, fuel, etc. The true measure of an efficient cleaning operation is not the price per pound of a cleaning product. Actual cleaning results and unit cleaning costs provide a more accurate measure.

Most other products including petroleum products, vegetable oils, tallow, lard, etc. can be cleaned following these five basic steps for fast and effective interior cleaning---

1. Drain the tank as much as possible and pre-rinse with hot water at 1800F.

2. Spin with a cleaning solution heated to at least 180°F. Terj at 6 - 8 oz. per gallon can be used on aluminum tankers or one of the aforementioned products will be effective on stainless steel tankers.

3. Rinse with hot or cold water as the proper end operation determines.

4. Clean valves and hoses.

5. Blow or air dry the tank interior whenever possible.

If your account is cleaning some products with only hot water, cold water or steam, you cannot be of help to him.

You may also find vapor cleaning used which has undoubtedly proven to be an excellent and economical method of tank cleaning. It has its limitations, since it cannot clean behind a layer, or bubble of water. On asphalt or tar and similar products, it is practically the only true economical method of removal. Recirculation of a solvent type cleaner can be used, but safety precautions should be established, since the spraying of volatile solvents can spark at the wrong time and be dangerous.

Deodorizing and Sanitizing Chemicals

Once the cleaning process is completed, tank trucks which have carried offensive smelling chemicals must be deodorized and, in the case of food transports, sanitized. In many cases, tankers are rejected by the tanker's prospective customer because of contamination by offensive odors and/or residues "left over" in the tanker, even though it has been chemically cleaned. odor causing chemicals can penetrate the pores of the tanker skin and rubber hoses and in some cases, become locked-in valve chambers.

These odors can be eliminated by using Milanco Odor Killer after the tanker has been washed. This can be done by adding Milanco Odor Killer to the final rinse water at the rate of 1 lb, to 50 gals. Another method that is effective calls for adding one packet of Milanco Odor Killer to a five gallon pail of water. This is then dumped into the tank truck and a steam line Is hooked up to the bottom of the tank. Once the steam line is cracked open, the vapors will carry the deodorizer up the walls of the tank and into the pump and valves. This will also freshen up an account's treatment pond where the effluent eventually winds up. odors emanating from the ground where effluent gets dumped will also be eliminated.

Additional benefits from this final process include reduction of downtime and elimination of additional cleaning cost for tankers that are rejected at the pick up site. This final process is your client's assurance that his tanker will pass any test for pH, odor or surface bacteria administered at the pick up site.

After the tank interior has been cleaned and deodorized the disinfectant/ algacide should then be applied. This is only necessary with food transports. The FDA - the EPA - the DOT and others have all influenced regulations governing the sanitation of food transports.

Conclusion

This information constitutes only a small portion of the many problems confronting haulers of chemical products. There are many individual situations that demand different cleaning procedures and different equipment designs if the situation is to be approached in an efficient, cost-effective manner. Your presentation should be tailored to reducing the customer's cost by reducing cleaning time and tanker rejections. The combination of gallons per minute, temperature, pressure, and impingement with the proper cleaning compounds is the formula for correct cleaning at the lowest cost per unit washed.