Q & A

"We have a filter that appears to have been in service for nearly two years without any indication of blocking, is this normal?"

While contaminant ingression varies according to environmental and production/maintenance activity, some filter manufacturers specify a life of six months. It is generally a good strategy to take an upstream and downstream particle count to ascertain if the filter is still working properly, if not replace the element.

Consider the maintenance history and try to establish an average life for previous elements as this will give some indication if two years is abnormal.

However, there are a number of ways in which the filter may fail without tripping the indicator, and this may lead the unwary to believe the filter is good value. Without a particle count program, it is almost impossible to determine a failed filter. Such failures as a collapsed element, split pleat, poor adhesion on the seam, a sticking by-pass valve or even a faulty indicator are typically not detectable without a particle count program to monitor changing contaminant levels.

Today's Tip

• Vacuum sampling of motor oils may cause fuel dilution to register lower than actual concentrations. The vacuum can encourage vaporization of the fuel during the sampling process.

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Book Bits

From the book "Lubrication for Industry":

All Lubricants Not Equal

This study was done in a large automotive assembly plant which was experiencing multiple air tool and hydraulic valve failures. Through the use of the work order management system, the investigations identified that the failures had started gradually and had intensified into a virtual line shutdown situation over a period of months (a line shutdown is measured in thousands of dollars per minute).

Wear particle analysis samples were taken at the lubrication delivery points where the mechanical failures were occurring, and at the plant lubricant storage facility where the clean lubricant was stored. Virgin stock samples were also obtained directly from the lubricant manufacturers. The results found all three samples showing markedly different results.

Further investigation found that lubricants were purchased from a variety of manufacturers based on viscosity specifications, e.g., hydraulic 32 weight oil. These virgin stocks were then used to "top up" the storage containers in the lubricant storage room. The topped-up lubricants would then be transferred to the lubricant dispensing equipment. The transfers would take place with the same transfer pump for all lubricants. Also, there were only two funnels for all lubricants. These funnels were not thoroughly cleaned between lubricant transfer use, thereby adding significantly to the contamination of the lubricants.

The problem was a compound one. Oils were being allowed to be mixed at the receiving stage as well as the transfer stages. Incompatibility of lubricants "stripped out" the additive package and neutralized other additives which rendered many of the lubricants ineffective. To solve the problem, a three- part solution was implemented.

1. The lubricant purchasing specification was re-written. The new specification was highly specific in that it named the actual lubricants as opposed to identifying only the weight or class lubricant.

2. All lubricant storage vessels in the lubricant storage area were labeled with the lubricant brand name and relevant information of the lubricant they contained.

3. New transfer pumps and funnels were purchased. Each individual lubricant stored was issued its own personal transfer pump and funnel. The pumps and funnels in turn were labeled with the lubricant brand name.

For more information about the book "Lubrication for Industry" go to:

http://www.noria.com/secure/product_detail.asp?catalogid=9

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