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Screening for Moisture: Crackle Test

Evan Zabawski | Senior Technical Advisor, TestOil

Screening for Moisture: Crackle Test

One of the easiest ways to measure the presence of free and emulsified water in oil is with the hot‐plate crackle test. An emulsion is the stable state of physical coexistence of chemically insoluble substances, like oil and water. Additives and impurities that lower the oil’s surface tension can serve as agents to strengthen the emulsion. Water is in a free state when undissolved globules of water are physically suspended in the oil.

For years, oil analysis laboratories have screened samples with the crackle test, performing more detailed analysis, such as the Karl Fischer test, only when the crackle test is positive.

In the crackle test, a drop of oil is placed on a hotplate that has been heated to approximately 400°F. The sample then bubbles, spits, crackles, or pops when moisture is present. If the crackle test is negative, it simply means that the level of water present in the sample is below the detection limit; it doesn’t necessarily mean the sample is void of water.

Sometimes the crackle test may not be appropriate and you would need a Karl Fischer test done on all samples from that machine. The crackle is not a scientific test but an estimate that is affected by oil type.


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About the Author

Evan Zabawski Senior Technical Advisor, TestOil

Evan is a Certified Lubrication Specialist. Evan has extensive experience training tradesmen and professionals in a variety of fields including: lubrication fundamentals, contamination control, condition monitoring, RCM/FMEA and used oil analysis. Evan has been a member of STLE for over 20 years, serving as Chair of the Alberta Section for 8 years, and also as an instructor of the Condition Monitoring course at STLE Annual Meetings. Currently, Evan has Editor of TLT Magazine, and have served as the Editor for The STLE Alberta Section’s Basic Handbook of Lubrication – Third Edition, and contributed as one of the editors for STLE/CRC’s Handbook of Lubrication and Tribology, Volume II: Theory and Design, Second Edition. Evan has published several technical papers and am also a member in good standing of API and ASTM.