FACTORS THAT INFLUENCE DETERIORATION CONTROL It is impossible to entirely prevent the introduction of organisms into working fluids;11 however, it is possible to minimize contamination o
Trang 2All preservatives do not function equally well in a particular product Sometimes a more expensive preservative is more economical than a cheaper one because the interval between treatments is greater and the amount of material required is less Sometimes it is more economical to purchase a more expensive coolant and treat it with a cheaper preservative than buying an expensive preservative and using it in a cheap coolant The purpose of microbiological control is to reduce costs, but companies have practiced coolant control without initiating studies to determine if costs are actually reduced Once an individual has learned to determine the microbial load of a working system and has selected the proper preservative, there are a number of things which should be kept in mind
FACTORS THAT INFLUENCE DETERIORATION CONTROL
It is impossible to entirely prevent the introduction of organisms into working fluids;11 however, it is possible to minimize contamination of a system Construction of a new plant offers an opportunity to take advantage of a number of factors which may influence coolant life Plants should never be placed downwind of sewage treatment plants, flour mills, bakeries, feed mills, fertilizer plants or cooling towers which may produce either airborne nutrients or contaminants
The internal construction of the plant should be engineered so that it can be cleaned properly with a minimum of effort Consideration should be given to the design of the circulation system, floor elevation, dragout recovery, coolant storage area, pipe work, pump rates, reclamation equipment and other factors,37,38 Machines should be selected which minimize coolant contact with workers and the environment Newly acquired reconditioned machines can be sources of major contamination problems and should be thoroughly steam cleaned before being put into operation
Many companies design their systems so that there is too much agitation of the coolant This practice is usually done in order to move chips or to prevent or reduce coolant odors Few individuals appear to recognize that the greater the agitation of a coolant, usually the greater the microbial attack.39 Circulation should be adequate for desired performance but
it should not be overdone
Petroleum-base fluids normally are subject to bacterial deterioration while synthetic and semisynthetic products are more likely to encounter mold (slime) problems Formaldehyde-releasing preservatives are somewhat weaker against molds than against bacteria.28,29,40Extra care must be taken when using this type of preservative in synthetic and semisynthetic coolants because if the system is improperly treated, slime problems can occur
A circulation system should never be underdosed41with a preservative Most antimicrobial agents will markedly stimulate growth when employed in low concentrations.42 The use of
a small amount of preservative in a system may produce more growth than if nothing is done
Preservatives should never be mixed indiscriminately Practically all combinations of the readily available preservatives are incompatible with each other and mixing them can result
in less control than using one product alone
Coolant control in one system cannot normally be applied to other systems.41Each system has characteristics which are unique for that system alone The character of each system must be learned through tests and observations
Machines, floors, circulation systems, and parts should be kept as clean as is possible Stock stored in outside yards may be dirty and serve as a source of contamination of the coolant Tote baskets holding parts should be designed so that the stock can be subjected
to high-pressure water jets prior to being moved to the machines
It is sometimes necessary to shut down machines or systems for extended periods of time
If the system is to be inactive for only a few days, it is best to treat with a biocide and
Trang 3continue to circulate the coolant If the shutdown period is going to be prolonged, and if it
is possible and practical, it is advisable to drain and clean the circulation system and leave
it dry until it is operated again If possible, the drained coolant may be used as makeup for working systems
There is a misconception that when a coolant develops odor or slime it has spoil and
is beyond recovery If other criteria are used, such as rust protection, tool life, emulsion stability or finish, they may indicate that the coolant is beyond salvage On the other hand, even though slime or odor has developed, if the engineering qualities are still satisfisfactory
it may be possible to save the system via effective preservative treatment
When a system which contains a great deal of slime or odor is under treatment, precautions should be taken The breakdown of millions of microbes killed by the preservative can produce considerable amounts of organic matter which produces frothing When this occurs foaming will start 24 to 48 hr after the addition of the preservative This is a temporary phenomenon which will last only a few hours Unfortunately the coolant is often discarded after the foam appears when the addition of a small amount of antifoam agent would have eliminated the problem
Pumps and filtration equipment should be watched when biocide treatment is underway
A system that has accumulated large amounts of slime can give trouble when this material
is dislodged in large masses This release can temporarily increase the viscosity of the coolant, placing an increased load upon the pump motors and it may plug lines and pumps These obstructing masses should be removed as soon as they are detected
Additional factors can influence rancidity control As confidence is gained in protecting working coolants, the engineer may wish to achieve even better coolant life by understanding these factors
General discussions of these factors have been published;2,17,38,43however, those interested
in more detained treatments can study reports which deal with the effects of coolant tem-perature,11,44water hardness,45,46water quality 17,47,48urine,17metals,38dragout,36hydraulic fluids,36,38 oil-water ratios,49 differences in the sensitivities of different systems to preserv-atives,50 and chelating agents.30 Those interested in medical problems51–53 or disposal problems54,55may wish to read these communications
Coolant control is not difficult to accomplish Doing nothing more than determining the microbial content of a working coolant at periodic intervals and adding a preservative when the count reaches a certain level can produce a significant increase in coolant life Where coolants have lasted a few weeks, it is possible to experience a doubling of coolant life Where coolants have functioned properly for several months, a 60% improvement in coolant life is not unusual Some users have already undertaken quality control of their fluids and two publications have appeared concerning their success in this area.10,56
REFERENCES
1 Kane, E L., A Chart for Recording and Analyzing Factors Influencing Coolant Life, ASLE Preprint No.
73AM-4C-2, American Society of Lubrication Engineers, Park Ridge, III., 1973.
2 Bennett, E O., The biological testing of cutting fluids, Lubr Eng., 30, 128, 1974.
3 Hill, E C., Gibbon, O., and Davies, P., Biocides for use in oil emulsions, Tribology, 121, June 1976.
4 Hill, E C., Some aspects of microbial degradation of aluminium rolling coolants, Proc 3rd Int Biodegrad.
Symp., 3, 243, 1976.
5 Holdon, R S., Microbial spoilage of engineering materials VI Improving monitoring and control,
Tri-bology 10, 273, 1977.
Trang 46 Yanis, R J and Wolfe, G F., Test procedures for the evaluation of culling fluids, Lubr Eng., 164,
April I960.
7 Hill, E C., Microbiological examination of petroleum products, Tribology, 5, February 1969.
8 Rossmoore, H W., Methylene blue reduction for rapid inplant detection of coolant breakdown, Int Biodetn.
Bull., 7, 147, 1971.
9 Rossmoore, H W., Holtzman, G H., and Kondek, L., Microbial ecology with a cutting edge, Proc.
3rd Int Biodegrad Symp., 3, 221, 1976.
10 McCoy, J S., A practical approach to central system control, Lubr Eng., 34, 180, 1978.
11 Kane, E L and Pfuhl, W., Preservation and preservatives in the aluminum hotrolling and beverage can
processing industry, Lubr Eng., 32, 249, 1976.
12 Bennett, E O., The deterioration of metal cutting fluids, Prog Ind Microbiol., 13, 121, 1974.
13 Tant, C O and Bennett, E O., The isolation of pathogenic bacteria from used emulsion oils, Appl.
Microbiol., 4, 332, 1956.
14 Tant, C O and Bennett, E O., The growth of aerobic bacteria in metal-cutting fluids, Appl Microbiol.,
6, 388, 1958.
15 Bennett E O., The role of sulfate-reducing bacteria in the deterioration of cutting emulsions, Lubr Eng.,
13, 215, 1957.
16 Kitzke, E D and McGray, R G., The occurrence of moulds in modern industrial cutting fluids, paper
presented at the I7th ASLE Meet., St Louis Preprint No 62 AM 4B-3, 1962.
17 Bennett, E O., The biology of metalworking fluids, Lubr Eng., 28, 237, 1972.
18 Rossmoore, H W and Holtzman, G H., Growth of fungi in cutting fluids, Dev Ind Microbiol., 15,
273, 1974.
19 Wort, M, D., Lloyd, G I., and Schofield, J., Microbiological examination of six industrial soluble oil
emulsion samples, Tribology, 35, 1976.
20 Guynes, G J and Bennett, E O., Bacterial deterioration of emulsion oils I Relationship between
aerohes and sulfate-reducing bacteria in deterioration, Appl Microbiol., 7, 117, 1959.
21 Isenberg, D L and Bennett, E O., Bacterial deterioration of emulsion oils II Nature of the relationship
between aerobes and sulfale-reducing bacteria, Appl Microbiol., 7, 121, 1959.
22 Vamos, E and Csop, A., The microbiological corrosive action of metal machining oils, Corros Week,
41, 1029, 1970.
23 Smith, T F H., Toxicological and microbiological aspects of cutting fluid preservatives, Lubr Eng., 25,
313, 1969.
24 Paulus, W., Problems encountered with formaldehyde-releasing compounds used as preservatives in aqueous
systems, especially lubricoolants — possible solutions to the problems, Proc 3rd Int Biodegrad Symp.,
3, 1075, 1976.
25 Pauli, O and Franke, G., Behavior and degradation of technical preservatives in the biological purification
of sewage, Biodeterioration of Materials, Vol 2, Haisted Press, New York, 1972, 52.
26 Voets, J P., Pipyn, P., Van Lancker, P., and Verstraete, W., Degradation of microbiocides under
different environmental conditions, J Appl Bacteriol., 40, 67, 1976.
27 Rossmoore, H W and Williams, B W., An evaluation of a laboratory and plant procedure for preservation
of cutting fluids, Biodetn Bull., 7, 55, 1971.
28 DeMare, J., Rossmoore, H W., and Smith, T H., Comparative study of triazine biocides, Dev Ind.
Microbiol., 13, 341, 1972.
29 Bennett, E O., Formaldehyde preservatives for cutting fluids, Int Biodetn Bull., 9, 95, 1973.
30 Izzat, I N and Bennett, E O., The Potentiation of the Antimicrobial Activities of Cutting Fluid
Preserv-atives by EDTA, Preprint No 78-AM-5C-1, American Society of Lubrication Engineers, Park Ridge, III.,
1978, 1.
31 Pivnick, H and Fabian, F W., Methods for testing the germicidal value of chemical compounds for
disinfecting soluble oil emulsions, Appl Microbiol., 1, 204, 1953.
32 Kitzke, E D and McGray, R J., Coolant microbiology: the role of industrial research, paper No 59AM
3A-3, 14th ASLE Natl Meet., Buffalo, 1959.
33 Brandeberry, L J and Myers, H V., Test procedures for compounds used as preservatives in industrial
coolants, Lubr Eng., 16, 161, 1960.
34 Himmelfarb, P and Scott, A., Simple circulating tank test for evaluation of germicides in cutting fluid
emulsions, Appl Microbiol., 16, 1437, 1968.
35 Rogers, M R., Kaplan, A M., and Baumont, E., A laboratory inplant analysis of a test procedure for
biocides in metalworking fluids, Lubr Eng., 31, 301, 1975.
36 Bennett, E O., Effect of Dragout and Hydraulic Fluid Contamination on Rancidity Control in Cutting
Fluids Preprint No 76-AM-18-1, American Society of Lubrication Engineers, Park Ridge, III., 1976, 1.
37 Smith, M D and West, C H., How Plant Practices Affect Employee Health in the Presence of
Metal-working Fluids American Society of Lubrication Engineers, Park Ridge, III., August 1969, 321.
Trang 538 Bennett, E O., Microbiological Aspects of Metalworking Fluids, Tech Pap No MR73-826, American
Society of Mechanical Engineers, New York, 1973, 1.
39 Rossmooore, H W., Sceszny, P., and Rossmoore, L A., Evaluation of Source of Bacterial Inoculum
in Development of a Cutting Fluid Test Procedure, No 76-AM-1B-2, American Society of Lubrication
Engineers, Park Ridge, III., 1976, 1.
40 Rossmoore, H W., De Mare, J., and Smith, T H F., Anti- and pro-microbial activity of
hexahydro-1,3,5-tris-2-hydroxyethyl-s-triazine in cutting fluid emulsions, in Biodeterioration of Materials, Vol 2,
Halsted Press, New York, 1972, 286.
41 Bennett, E O., Factors involved in the preservation of metal cutting fluids, Dev Ind Microbiol., 3, 273,
1961.
42 Bauerle, R H and Bennett, E O., The effects of 2,4-dinitrophenol an the oxidation of fatty acids by
Pseudomonus aeruginsa, Ant van Leeuwenhoek J., 26, 225, I960.
43 Hill, E C., Biodeterioration of Metal Working Fluids and Its Significance, Publ No MR72-214, American
Society of Mechanical Engineers, New York, 1972 1.
44 Hill, E C., The significance and control of microorganisms in rolling mill oils and emulsions, Met Mater.,
294, September 1967.
45 Feisal, E V and Bennett, E O., The effect of water hardness on the growth of Pseudomonas aeruginosa
in metal culling fluids, J Appl Bacterial., 24, 125, 1961.
46 Bennett, E O., The Effect of Water Hardness on the Deterioration of Cutting Fluids, Tech Pap No.
MR72-226, Society of Mechanical Engineers, New York, 1972, 1.
47 Humnicky, S., Pure water improves coolant mix, Tooling Prod., 48, February 1971.
48 Bennett, E O., Water quality and coolant life, Lubr Eng., 30, 549, 1974.
49 Carlson, V and Bennett, E O., The relationship between the oil-water ratio and the effectiveness of
inhibitors in oil soluble emulsions, Lubr Eng., 16, 572, I960.
50 Bennett, E O., Adamson, C E., and Feisal, V E., Factors involved in the control of microbial
deterioration I Variation in sensitivity of different strains of the same species, Appl Microbiol., 7, 368,
1959.
51 Bennett, E O and Wheeler, H O., Survival of bacteria in cutting oil, Appl Microbiol., 2, 368, 1954.
52 Rossmoore, H W and Williams, B W., Survival of coagulase-positive staphylococci in soluble cutting
oils, Health Lab Sci., 4, 160, 1967.
53 Holdom, R S., Microbial spoilage of engineering materials Are infected oil emulsions a health hazard to
workers and to the public? Tribology, 9, 271, 1976.
54 Bennett, E O., The disposal of metal cutting fluids, Lubr Eng., 29, 300, 1973.
55 Bennett, E O., The Disposal of Metal Cutting Fluids, Publ No 73AM-4C-EB, American Society of
Lubrication Engineers, Park Ridge, III., 1973, 1.
56 Vermooten, C A L., Microbiological destruction of soluble oil emulsion in steel plant hydraulic systems,
paper read at South African Soc Plant Pathol Microbiol Meet., 1975.
Trang 6LUBRICANT APPLICATION METHODS
Edward J Gesdorf
INTRODUCTION
Modern lubrication standards for industrial equipment in mass production industries such
as automotive, steel, mining, rubber, etc usually start with the following goals: safety of personnel, uninterrupted production, extended machinery life, and good housekeeping A fifth item could easily be added — a reduction in operating costs Since the days of low-cost labor and lubricants are gone, it now becomes extremely important to select the most efficient method of applying lubricants
TRADITIONAL LUBRICANT APPLICATION DEVICES
Some of the older, simple lubricant application devices include:
1 Oil squirt can
2 Screw-type grease gun
3 Grease gun
4 Drop oiler
5 Vibrating pin bottle oiler
6 Thermal oiler
7 Wick-pad and waste-feed oilers
8 Splash-lubrication system
9 Ring, chain, and collar oilers
10 Mechanical positive-feed
Design, selection, and maintenance of this equipment is covered in reference material.1,2 During the early days of the industrial revolution the only devices available for applying oil
or grease to a bearing were oil and grease cups as shown in Figure 1 To eliminate their feast or famine nature, automatic pressure feeding grease cups were introduced, as illustrated
in Figure 2
In this device, the spring on top of the large piston exerts a constant pressure on the lubricant in the cup This pressure forces the lubricant around the screw thread on the reservoir pin, which is closely fitted to the outlet bore As grease is discharged to the bearing, the lowering compression of the spring is compensated by the screw thread of the resistance pin passing out of the discharge bore, lowering the resistance to flow By this method a constant feed of grease is provided to the bearing
The constant pressure supplied by the spring, combined with a restricted orifice at the outlet, caused many greases to bleed or separate oil from the soap The cup would then load
up with a cake of hard soap preventing further delivery of lubricant Special grease was therefore required to ensure proper operation of the device, whether the grease was suitable for the bearing or not While many of these grease cups performed an outstanding job, they suffered limitations for universal application
During this period, mechanical force-feed lubricators (Figure 3) came into use These devices were originally designed for engine room lubrication where they still serve better than any other type of lubricator Today many forced-feed lubricator applications have been incorporated in centralized systems This enables up to several hundred bearings to be served without the necessity of running a bundle of pipes or tubing from one central box
Copyright © 1983 CRC Press LLC
Trang 7in moving from right to left, changes the porting at its center section to permit a flow of pressure to the left end of the lower piston to move to the right, displacing the lubricant in the right end of the bore to a bearing
In following the foregoing sequence, a continuous cycling mechanism operates as long
as there is flow from the pump
Progressive Reversing System
Figure 7 illustrates a loop system which operates on the principle of reversible flow in
FIGURE 4 Multiple tube system.
Copyright © 1983 CRC Press LLC
Trang 8TABLE 1 COMPARISON OF SIX SYSTEM PRINCIPLES
Features
Adjustable measuring valves Measuring valves operate Measuring valve actuation Metering principle Measuring valve indicators Measuring valve piston sealing System will handle grease System will handle oil Can add or subtract lube points economically Economical monitoring — main supply lines Measuring valve monitoring
Currently popular
Copyright © 1983 CRC Press LLC
Trang 9the main supply line The measuring valves are progressive and nonadjustable, with indication
at the end of the loop
The main system elements consist of a reservoir, pump, four-way valve, main supply
FIGURE 6 Progressive system — nonreversing.
FIGURE 5 Single-line system, spring-actuated valve.
Copyright © 1983 CRC Press LLC
Trang 10effective on the top side of the pilot piston in the measuring valve, causing it to move downward After a certain amount of travel, an angle port is opened permitting lubricant to flow into the main measuring cylinder, forcing the main piston downward As the main piston moves downward, lubricant in the lower portion of the cylinder is forced through a second angle port and out the discharge port to a bearing Pumping is continued until all measuring valves have operated
To recycle the system, the hand lever of the four-way valve is shifted 90° which relieves the pressure in line 1 back to the reservoir and ports the pump to line 2 As pressure is developed in line 2, the measuring valve operation sequence described in the foregoing is repeated but with the valve pistons moving in the opposite direction Indicator stems attached
to the main pistons of the measuring valves provide a means for periodic inspection of valve operation Valve discharge adjustment is accomplished with two flat adjusting screws in the packing gland which control main piston travel
Orifice Oil System
Figure 9 illustrates an orifice metering system for oil which operates on the principle of pressurizing a common main supply line rapidly and bleeding the pressure off through various-sized orifices The metering orifices operate independently of each other and are nonadjustable The main system elements consist of a reservoir, pump, main supply line, and orifice meter assemblies
The lubricator is of the spring discharge type and is operated by pushing the lever down which raises the piston and compresses a spring By releasing the lever a fixed volume of oil is discharged into the supply line which is then dissipated through the orifice meters at the bearings
Orifice Oil Mist System
Figure 10 illustrates an orifice metering system for oil mist Oil is broken up into fine particles and dispersed in air for conveying through pipeline to the point of application The main system elements are a filter and water separator, solenoid-operated air valve, air pressure regulator, misting head, oil reservoir, mist distribution manifold, and reclassifying fittings
at the bearings
FIGURE 8 Dual line system.
Copyright © 1983 CRC Press LLC