Africa's road transport operators are going to have to clean up their act when it comes to workshop, lubrication, fuel and tool hygiene. That's the clear message delivered to delegates at a recent SA Institute of Tribology workshop on Fluid Contamination Control.
FleetWatch's technical correspondent Dave Scott was there and brings back some valuable lessons for our readers.
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This chart shows how cleanliness and excellent filtration will extend component life.
Source: Pall Corporation |
New trucking technologies from our major supplies demand filtration below 5 micron for all fluids, diesel and lubricants used in a truck's power train - and it's a real strain in Africa to work that clean. To give an idea of what we're talking about - one micron equals 1-millionth of a metre or 25 thousandth of an inch. Considering that a human hair is around 50 micron, abrasive particles are really not visible when they are only a 10th the size of a hair. It's invisible dirt and water that halves the life of hard-working power trains.
The pervasive rumour that we have 'dirty diesel' must be squashed. Every day I see dirty and sloppy housekeeping that introduces every kind of contaminant into a truck's highly stressed components. Just a few examples are dipsticks wiped with dirty rags, tools lying in sawdust and lubricants incorrectly stored that draw moisture into drums.
Some companies have recognised that contamination control needs more than just a broom. It cannot be left to chance with the hope that a cultural factor will ensure spotless working conditions. Contamination control officers - or 'mechanical engineering matrons' - are starting to appear as a dedicated task and part of a management strategic initiative to prolong equipment life for the lowest operating costs.
Contamination with lubrication changes
Draining used oil and adding new lubrication into any system is a risky business, magnified by untrained staff that often cannot comprehend the need for cleanliness. This is what can happen:
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The wrong or incompatible lubricant is introduced. Make sure that lubrication staff are literate, trained and even then, colour-code products for correct application.
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A contaminated lubricant is introduced. The cleanliness of the dispensing system is compromised.
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Settled contaminants in tank/sump floors and inactive zones get re-suspended: The system never gets flushed out.
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Human failures: Dead-heading pumps on re-start, cleaning solvents not removed and introduction of particle contaminants.
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Acid attack
Oxidation is an unavoidable process in engines as lubricants degrade through usage and time and form unwanted compounds. Some of these remain present in the lubricant to cause deterioration of the lubricant and the lubricated system while other compounds are volatile and flash off leaving slightly thickened oil behind. Nitrous and sulphur oxides are present in crankcase lubricants resulting from combustion processes. All these oxides need is water to form acid and corrode bearings.
Lubricant drums, incorrectly stored with the bung upright in an open yard, expand and contract to draw in moisture. Some of this water remains free and some emulsifies with the lubricant. It just gets added to engines when it is decanted for use and because we don't see an immediate problem, sloppy housekeeping goes unnoticed which results in acid formation in an engine.
The forgotten breather
One of the most ignored components of any fuel storage tank or working machinery is the breather. According to hydraulic expert Garnett Cross: "The breather on new equipment is often overlooked for its entire working life resulting in hydraulic pump cavitation because a dirty breather creates pump starvation. A breather is bi-directional - it allows working pressure to escape and draws in from the outside when a machine cools down to attract contaminants unless properly filtered."
A diesel engine breather requires testing for functionality every six months and bi-annual replacement. Gearbox and axle breathers are also vital in protecting components from the ingress of particle contamination while managing pressure build-up.
According to Olaf Voigt, industrial marketing manager of filtration specialists, Pall South Africa, modern fuel injection equipment runs at very high pressures that demand fuel filtration below 3 microns. "To protect expensive injectors from premature wear, we recommend that 3 micron fuel tank breathers are fitted to diesel fuel tanks with the breather situated high away from the tank," he says.
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Olaf Voigt, industrial marketing manager, Pall South Africa: "It's a fact that the more efficient a filter, the higher the price. Nominal rating for filtration has no value as it is an arbitrary value with no ISO standard. The most meaningful measurement is the Beta Ratio (ß) - the ratio between upstream and downstream particle counts. The higher the ß ratio, the better the filter process". |
Where are you?
Technical staff should assess the strategic status of their fleet maintenance operations. Where is your maintenance strategy on this scale?
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Breakdown level - driven by crisis and numerous on-road failures.
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Preventive - the number of breakdowns is being contained but there's a dearth of information to be able to predict preventive maintenance standards.
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Predictive - you're not only preventing breakdowns but you can actually predict when components will fail.
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Pro-active - you're not only in predictive mode but you are doing research and sharing your industry findings with your suppliers who are partners in your maintenance programmes.
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Early stages of contamination control will limit crisis breakdowns but the long-term effects can be seen in both predictive and pro-active strategies that impact on vehicle power trains over years not just months. After all, the idea of contamination control is to extend component life by years.
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Hannes Berry, contamination control officer, Barloworld Equipment: "Industry trends are for employment of electro-hydraulic systems employing much higher pressures and tighter clearances. The result is that today's fluid systems are more sensitive to contamination."
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How to start attacking contamination
To establish an effective contamination exclusion programme, you need to design an action plan that concentrates on these fundamental modes which contribute to the problem:
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Contamination during transport, storage and dispensing - approved, finished fluid products follow long routes to the market and to the points of final consumption. They can easily be exposed to contamination during this process.
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Contamination by people -
implanted during manufacturing or induced in the field during maintenance repair and overhaul.
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System generated contamination - created chemically or by absorption.
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Machine ingested contamination - introduced by dust, air and water inhalation, or through particles and microbes migrating from the environment.
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My advice to you is to create accurate information databases recording wear and failure rates, replacements and trend lines. Contamination control carries a cost factor that must have a proven payback. Only valid information will allow predictive and pro-active maintenance strategies to be implemented.
Top management must instil pride and discipline in the workplace and it must become competitive and fun to be clean. Sawdust belongs in a butcher-shop - sawdust blowing around a workshop floor is a real no-no alongside dirty tools, filthy change-rooms and toilets.
The case rests with the accompanying chart that shows how cleanliness and excellent (not cheap) filtration will extend component life. This is from a study directed by Dr. P.B. Macpherson in the United Kingdom which demonstrates the relationship between the control of clearance size particles and the relative fatigue life of rolling contact bearings. Tests on roller bearings showed that as the filter rating decreases from 40-micron down to 3-micron, bearing fatigue life increases exponentially. You make the choice!
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Siduduzo Mncwango, Engen product engineer, industrial: "Contaminants are any unwanted influences that destroy the integrity of a system and cleanliness is a quantitative value measurement that can be done by instrument. We must remove subjective contamination judgements." |
