Q & A

Water Contamination Removal

"Our lube oil testing/analysis often shows levels of water present in the oil. We are considering the purchase of portable equipment suitable for the removal of water from lube and hydraulic oil systems. I have also been told by some people that some separators can only remove water down to the water saturation level of the oil. Is there a preferred method for removing water from oil in a lube or hydraulic circulating system? How much water can be removed by these methods?"

Water in any lubrication system is bad news. In hydraulic systems, it can result in vaporous pump cavitation, corrosion and valve stiction, while in circulating lube oil systems it can cause oil film strength loss, rusting and other serious mechanical problems.

The effects of water on the oil are often overlooked. Excessive water contamination can result in premature oil oxidation and promote the build up of sludge and varnish. In ester-based fluids, it can result in the hydrolytic destruction of the base fluid resulting in the formation of corrosive acids. In some circumstances, water can also strip additives from the oil through water washing or hydrolysis resulting in premature oil degradation.

For these reasons, the best strategy when it comes to water is to monitor and control the root cause of the water ingression. This can be achieved by ensuring that all seal and breathers are in good shape (consider using desiccant style breathers), lube tank hatches are closed and sealed properly and that top-up oil is stored and handled properly.

Water can exist in three phases in an oil, free, emulsified and dissolved. Free and emulsified water cause the most damage so a good rule of thumb is to keep moisture levels below the saturation point so that all the water is in the dissolved state. For typical mineral-based industrial oils, this is typically 200-300 ppm.

The most effective way of achieving this is to use a vacuum dehydration unit. These systems are capable of removing free and emulsified water as well as up to 70-80% of the dissolved water. For a typical hydraulic fluid, this can mean water levels as low as 30-50 PPM (0.003-0.005%). Alternatively, many companies are reporting success with vapor extraction devices mounting on tank tops. Some of these devices work similar to air conditioners in removing humid air from tank headspaces.

For more information about vacuum dehydrators go to:

http://www.lube-tips.com/links/water1.html

Today's Tip

• Do not use succinic acid type R&O fluids in ammonia refrigeration systems. Ammonia leaking past the seal will react to form ammonia succinate, a sludge like material that could cause valve sticking and premature failure. Tip submitted by John Cannella, American Refining Group. Thanks John!
  

Each tip published will earn the sender $10. Send your tips to webmaster@noria.com or fax to 918-746-0925.

Book Bits

"An additive is a compound that enhances some property of, or imparts some new property to, the base fluid. In this way, a base stock that cannot meet operational requirements of a tribological fluid system can be modified through additives. In some hydraulic fluid formulations, the additive volume may constitute as much as 20 percent of the final composition. The more important types of additives include anti-oxidants, anti-wear additives, corrosion inhibitors, viscosity index improvers, and foam suppressants.

Antioxidants prolong the induction period of a base oil in the presence of oxidizing conditions and catalyst metals at elevated temperatures. The additive is consumed and degradation products increase not only with increasing and sustained temperature, but also with increases in mechanical agitation or turbulence and contamination -- air, water, metallic particles, and dust."

For more information about "Fluid Contamination Control" go to:

http://www.noria.com/secure/product_detail.asp?catalogid=47

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Lube-Tips is published by Noria Corporation. Oil Analysis and Lubrication Experts