In This Issue:

• Up Front: Faulty Filter Change Indicator

• Book Bits: Synthetics Not Always Better

• Today's Tip: How to Speed Up Oil Changes

• Q & A: Oil Analysis on Small Sump Systems
  

Up Front

Faulty Filter Change Indicator

On most of our turbine bearing lubrication systems, we have in-line duplex filter systems. The filters are changed or cleaned in these systems on the basis of differential pressure across them. The more the filters get clogged with particles, the greater the differential pressure (DP) increases. If the DP crosses a recommended value, then it is time for filter change to prevent a rupture.

A sudden decrease in differential pressure indicates that the filter likely has given way. At that time, the filter should be changed immediately, as dirty oil will continue to bypass the filtration system. (Submitted by Indranil Dutta, Tata Iron and Steel Company. Thanks Indranil!)

Editors Note: Remember that differential pressure across a filter is a good indicator of when to change a filter to prevent damage, but should not be relied upon for ensuring that filtration is occuring appropriately. It's a good idea to supplement differential pressure checks with consistent and reliable particle counting. Often the earliest indication that the filter has become damaged or otherwise ineffective is a rising particle count.

Each Up Front story published will earn the sender $50. Submit a case study, experience or lesson learned. Or e-mail info@noria.com. Let us hear from you.

Book Bits

Synthetics Not Always Better

From "Synthetic Lubricants and High-Performance Functional Fluids":

Synthetic gear lubricants are used whenever mineral gear lubricants have reached their performance limit and can no longer meet the requirements. These requirements include operation at very low or high temperatures, extremely high loads and extraordinary ambient conditions.

There may even be special requirements such as low flammability. Even though many properties of mineral oils can be improved by means of additives, it is not possible to exert unlimited influence on all their properties. This applies especially to properties that depend on the chemical structure of the lubricant, such as thermal resistance, low temperature behavior, flash point and evaporation losses. Synthetic gear lubricants provide a number of advantages; however, they do not necessarily outperform mineral oils in all respects and may even result in some practical drawbacks despite their advantages.

More information about "Synthetic Lubricants and High-Performance Functional Fluids".

Today's Tip

• Use your circulation pump to speed up oil changes in large circulation systems. Install a tee and two isolating shut-off valves downstream of your circulating pump. When draining your reservoir, connect the hose to this tee and use your pump to pump the oil from your reservoir to the scrap oil truck. Especially helpful for large, below-ground level systems. (Submitted by Rodger Shaffer, Manufacturing Engineer, Timken Latrobe Steel. Thanks. Rodger!)

Each tip published will earn the sender $25. Submit your tip.

Q & A

Oil Analysis on Small Sump Systems

"We have some systems in our plant that hold only a couple of quarts of oil. Is it worth conducting oil analysis on these units? By the time we get a sample, we have to replace most of the oil anyway."

On small sump systems, taking an oil sample with proper flushing often represents an oil change. How can the tests be justified? In these cases, we are less interested in the condition of the oil, than in what the oil can tell us about the condition of the system it is intended to protect.

Statistical analysis by a trained analyst may help optimize oil change intervals if sufficient population size is available and hours of operation or other use data is maintained; however, tests looking for evidence of contamination and destructive wear are the most powerful ones. Avoid discarding your best source of information about machine health.

Oil is a powerful messenger, especially in small sump systems because the signal is highly concentrated in the relatively small volume of oil.

Adam Davis, Technical Consultant, Noria Corporation