Wednesday, January 5, 2011

Moisture Testing in Petroleum Products

Moisture Analysis in Petroleum Products

Moisture is a constant nuisance in petroleum products. Moisture can affect the efficiency of lubricants and prematurely wear system parts that are expensive to replace and maintain. Testing for the moisture content in oils is a necessity to maintain oil systems and to detect moisture problems before they arise.

Moisture can enter an oil system a variety of ways. The simplest is in the process of adding or replacing oil and/or filters. Even if the oil system is closed, large amounts of moisture can enter through condensation in oil and filter storage. Oil can also absorb moisture from humid air depending on humidity and temperature. Any oxidation or combustion reaction can lead to water as a byproduct and can accumulate in the oil. Even the most carefully maintained system is vulnerable to moisture contamination.

All oils have a saturation point where they are able to hold a certain amount of dissolved moisture. This saturation point varies depending on polar additives present in the oil; as the water finds the polar molecules to collect around. Only after this saturation point is met is the presence of moisture in oil visible; either as an emulsion or as a layer In the oil.

Water has a variety of effects on oil systems. The most common is premature bearing wear. In large amounts moisture can lower oil viscosity, which can lead to bearing wear. It is also believed that moisture is absorbed into tiny fissures in the bearings and strips hydrogen from the metal, causing degradation. Even a small amount of moisture in a system can significantly affect bearing life.

Minute concentrations of moisture can also curtail the effect of certain additives in a system, especially oxidation inhibitors. As mentioned; water is attracted to polar molecules in a system, this can lead to decreased effectiveness of any polar additives. Some byproducts of hydrolysis reactions with additives can lead to acids, varnish, and sludge buildup which can prematurely clog filters.

Moisture in oil systems is a constant hazard that must be carefully monitored. The Computrac® Vapor Pro® Fx Moisture Specific Analyzer is capable of detecting moisture in most petroleum products quickly and easily and is approved for use with ASTM D7546-09 to detect moisture in lubricating oils as low as 10ppm up to 100% moisture.

Manuel Oropeza, Chemist
Arizona Instrument LLC

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