"We are experiencing problems in reaching our contamination targets on gearbox lubrication oil systems. Finer filters have been recommended on the filter carts. Is this a good idea?"

Before upgrading filtration, be sure to eliminate factors that could cause poor particle count results. Ask yourself the following questions:

* Are your samples being drawn correctly?  

* Are the supplied bottles sufficiently clean for your targets?  

* If you are using a particle counter onsite, is it calibrated?  

* Are there solid suspensions such as EP additives (moly, graphite, boron, etc.) in your lubricant?

Next, you need to identify the cause of elevated particle counts by answering these subsequent questions:

* Do you have contamination control procedures for storage and dispensing?

* Is the filter cart being used for the correct amount of time and frequency?

* Is there a need for better-quality breathers and seals? 

* Is there a chance of chemical or moisture contamination that may be forming emulsions in the oil?

* Are the alignment and balance correct?

* Are you using the right grade of lubricant?

If all of the above is in order and your targets are set correctly according to your reliability, safety and environmental concerns, then perhaps a small permanent-mount off-line system may address the problem. Just be sure that all the above checks have been made before spending money on upgrading the system filters.