How to Avoid Particulate Contamination Michelle Allis

Tag : oil containers
How to Avoid Particulate Contamination Michelle Allis, Wearcheck Africa, a Member of the Set Point Group
I t is widely accepted that oil contamination is one of the majorcauses of component failure. When practicing proactive maintenance,it therefore makes sense to give oil cleanliness a high priority.By maintaining a high level of oil cleanliness, effects such asmachinery failure, resultant downtime and expensive repair costscan be kept to a minimum.
There are many factors to consider when cleaning up your act. Thefirst and most important place to start is at the source: the newoil. Oil could be contaminated when it leaves the refinery, duringtransportation or during the transfer to the end-user's or vendor'stanks. But more often than not, it is the manner in which the oilis stored by the user that results in new oil contamination.
Oil Storage
Oil storage is an important factor to consider when implementingproactive maintenance, but it is usually at the bottom of the listof priorities or overlooked completely. Many times, the area andmanner in which the oil is stored can introduce contamination. Sohow do you ensure that this does not happen? Let's take a closerlook at proper oil storage conditions.
The most common oil container used by the oil industry is the210-liter (55.5-gallon) drum. Filled with oil, it weighsapproximately 220 kilograms (485 pounds). These drums should behandled carefully to prevent damage to the drums, causing them topuncture or burst. Containers should be moved immediately to astorage area and remain sealed until needed. Oil drums orcontainers should be stored indoors whenever possible.
To avoid contamination when storing oil outdoors:
Do not store the drums outside indefinitely, because drums can rustand contaminate oil.
Ensure bungs are tight and that drum seams do not deteriorate. Thiscan occur because temperature changes lead to expansion andcontraction of the metal, causing oil leaks or contamination.
Keep drums or containers as dry as possible and away from water. Donot allow water to accumulate on any part of the container. Thiswater can be drawn into the container when changing temperaturescause pressure changes within the drum or container.
Store the drums under a roof, a lean-to or cover with a tarp.
Before removing bungs, dry and clean around the bung areas toprevent contamination with dirt and water - the two most common anddestructive contaminants in any environment.
Lay the drums on their sides, on a specially constructed rack ifpossible. Make sure that the bungs are in the 3 o'clock and 9o'clock positions. This generally ensures that the content of thedrum is above the bung level. This minimizes water (and dirt) entryand stops the seal from drying out. If drums must be stored uprightwithout any protection from the elements, tilt them slightly andmake sure the tilt is parallel to the 3 o'clock/9 o'clock bungline. This prevents water from collecting around the bungs.

When storing oil containers or drums indoors, remember thefollowing tips:
The storage area should be a cool, dry area free from extremetemperatures.
Keep the storage area clean at all times, with a formal cleaningschedule in place.
Minimize the presence of any contaminants. Contaminants couldresult from manufacturing processes, the environment, etc.
Oils can also be stored in bulk storage tanks. It is often easierto maintain low particulate contamination levels when oils arestored in bulk tanks because they are normally closed to theatmosphere and the oil is dispensed via a pump or tap. Ensure theseals are intact and fitted with desiccant (recommended) breathers. Oil Dispensing
Contamination due to dirty top-up containers or dispensingequipment is a common problem. As with most of the points raisedwith storage, hygiene and common sense are what count. Dispensingequipment should be kept clean to minimize contamination of theoil. Keep in mind these few points:
Make sure pumps and portable lines are kept clean and are stored ina clean environment.
Avoid topping up and filling in exposed areas.
If top-up containers must be used, make sure they are clean and notleft open to the elements. Avoid mixing different oils in thesecontainers.
Quick-coupling fillers will ensure that environmental contaminantsdo not enter lubrication systems.
A number of companies produce utility cans for topping-up purposes.These have lid and spout designs that keep contaminants out, andsome have a pressurized dispenser.
Clean around filler caps before removing.
Make sure the tops of drums are clean and free from dirt and waterbefore opening.
Once sufficient oil storage has been established, the next placefor oil particulate contamination to occur is once the oil is inthe machine or component. This can happen in many ways. Open ventsprovide an easy means for dirt to enter machines. Faulty breathersare a common source of particulate contamination. Oil leaks ordamaged seals are also culprits. Remember, if oil is able to leakout of a system, contaminants are able to enter the system. Repairdamaged seals or oil leaks as soon as possible.
Internal Contamination
Some form of internal particulate contamination is inevitable andcan denote a problem with the machine/component. Internalparticulate contamination includes any particles that contaminatethe oil once it has been placed in the closed lubricated system -for example, wear particles, seal material, etc. When externalparticulate contamination is under control, a high particle countprovides an early warning for an abnormal wear situationdeveloping.
Particles, especially catalytic metal particles like copper, ironand lead, increase the oxidation rate. These particles also stripthe oil of its antiwear additives, extreme pressure additives, rustinhibitors and dispersants. Numerous small particles in stablesuspension can cause the oil's viscosity to increase and maypromote foaming.
These particles are abrasive. As with all particulate contaminants,once in the oil, they accelerate the wear rate dramatically becauseabrasive wear can cause a chain reaction in lubricated machinery.The typical chain reaction is:
Abrasive wear particles become work hardened.
Work hardened particles produce more particles.
New particles become work hardened.
Chain reaction occurs until the particles are removed by filtrationor the machine fails.
It is, therefore, imperative to monitor oil cleanliness and keepparticulate contamination to a minimum. This is accomplished byimplementing a contamination control program in these easy steps: Contamination Prevention
After ensuring oil is free from contamination, consider the timeswhen servicing the machine becomes necessary. When componentchanges or work is performed on the machine, make sure that all newcomponents are free from contamination and that furthercontamination does not enter the machine during servicing. Ensurethat all seals and breathers remain intact to prevent contaminantentry. Contamination Removal
Contamination removal is accomplished with filters and filtrationsystems or oil draining and discarding. Each application must beevaluated when deciding which option is more cost-effective. Usingfilters to achieve target cleanliness levels does not alwaysrequire the best or most expensive filter. A cheaper filter usedcorrectly may produce the desired results at a lower cost. Theeffectiveness of a filter or filtration system can be tested bytaking representative oil samples from before and after the filter. Monitoring Cleanliness Levels
For effective monitoring of the oil, check for cleanliness levelsin the machine as well as at several other points, such as new oilsources, bulk tanks or stored lubricants, or oil in service inequipment.
To monitor the level of contamination, test the oil and obtain aparticle count. Different instruments using different methods areavailable to test particle count. Wearcheck uses the most commontype of automatic particle counter, which operates on a lightblockage principle. In this particle count test, the total numberof particles, irrespective of origin, are counted in a number ofsizes, ranging from greater than 5 to 100 microns.
The results are expressed as the total number of particles permilliliter of oil in the various specified size ranges. Acleanliness rating is also reported. The cleanliness rating isexpressed as a two-number code X/Y, where X represents the totalnumber of particles per ml greater than 5 microns and Y representsthe total number of particles per ml greater than 15 microns.
Target Cleanliness Levels
For warranty purposes, certain manufacturers have establishedmaximum cleanliness ratings for their equipment. It is, therefore,difficult to know what the optimum cleanliness level is for yourmachines. Each machinery class has an appropriate oil cleanlinesslevel for that application. In general, machines with tightclearances benefit greatly from clean oil.
It takes time to monitor results and choose an exact level if youhaven't been given one by the manufacturer. Be realistic andconsider what is cost-effective when setting target cleanlinesslevels. It makes no sense to expect such high cleanliness levelsthat you spend more money discarding or filtering your oil than itwould cost to replace the machine in the event of a failure.
Sampling technique is of utmost importance when monitoringcleanliness levels. Sometimes an oil may have a high particle countresult, but the actual oil in the machine is perfectly clean. Thiscould be the result of two scenarios: First Scenario
Ensure that the oil sample taken is representative of the oil inthe machine. The oil should be well mixed when the sample is takenand no external contamination should be introduced during sampling.This external contamination could result from factors such as:
A dusty environment
A manufacturing process that produces particulate contamination
The oil not being well mixed and sediment from the tank bottomdraining into the oil sample bottle
A dirty sample valve
Dirty sampling equipment, especially when samples are transferredfrom another sampling container
Sample bottle caps not being replaced immediately after the sampleis taken
Dirty sample bottles Second Scenario
Consider the laboratory method to obtain particle count data.Wearcheck operates an optical particle counter using the lightblockage technique. This involves passing a laser beam through acontrolled stream of oil, measuring the amount of light blocked byindividual particles as they pass through the beam. Obviously,larger particles block more light than smaller ones, making sizeinformation relatively easy to obtain.
This method is sensitive and has some limitations. Particle countdata is inflated by the presence of water droplets or gas bubblesin the sample because these are seen as particles. The laser cannotpass through dark or extremely contaminated samples, making themimpossible to measure.
It is important to look at the appearance of the oil as well asother laboratory tests, such as water concentration and anycomments based upon a microscopic examination, before reacting toan abnormal particle count result. It is also important to ensurethat the sample is taken in the same manner and from the samesampling point each time a piece of equipment is sampled.
This consistency allows samples to be compared with confidence(compare apples to apples). Randomly sampling a machine from up anddownstream of a filter can produce a confusing set of laboratoryresults if no sampling point information is included with thesample.
To summarize, set target cleanliness levels, achieve targetcleanliness levels with continuous exclusion and removal ofcontaminants, and monitor contamination levels regularly to assureconformance to standards. Benefits
Better lubrication leads to increased profits. Lubricants free fromcontamination provide better service to machines. Properlylubricated machines will provide better, more reliable andprofitable service to the owner or operator. Why then iscontamination control given such a low priority in most proactivemaintenance programs?
This is largely due to a lack of understanding of contamination,its consequences and how to control it. Proactive maintenancerequires a long-term investment in machines and people. A smallamount of particulate contamination in a machine may not lead to aninstant failure or halt operation today, but it will invariablyshorten the machine's life. When the machine finally fails, it isdifficult to determine or even prove loss of life due toparticulate contamination.
Education is the most important step on a journey of successfulcontamination control. All personnel must be educated about theirroles in the process and the benefits of reaching the destination.Teamwork is imperative and an educated, dedicated team will createan efficient, cost-saving contamination control program. The ruleof thumb is that it costs 10 times as much to remove theparticulate contamination than to prevent it from occurring in thefirst place.
The bottom line is this: Clean up your act and you will achievegreater machine availability and utilization. Reduced operatingcosts and increased profits will follow naturally. About the Author

Michelle Allis is senior diagnostician for Wearcheck Africa, amember of the Set Point group. For more information, visit www.wearcheck.co.za . Please reference this article as:
Michelle Allis, Wearcheck Africa, a Member of the Set Point Group,"How to Avoid Particulate Contamination". Machinery Lubrication Magazine. May 2008 Issue Number: 200805
Machinery Lubrication
Handling and Disposal