A field and lab screening method in which a drop of oil goes onto a hot plate at around 130 to 160 C. Water flashing to steam makes an audible crackle and visible bubbling, which shows free or emulsified water above roughly 500 to 1000 ppm. It is crude but fast, so labs use it to decide which samples go on to Karl Fischer, and techs run it right at the machine.
Crackle test popped like bacon grease, there's water in that gearbox, send a bottle for KF.
No crackle does not mean dry: water dissolved below the oil's saturation point will not pop.
Also heard as
- hot plate test
- hot plate crackle
- sputter test
Related terms
Karl Fischer titration
Chemical titration that measures water in oil down to about 10 parts per million.
Milkshake
Oil turned milky or creamy by emulsified water, seen in gearboxes, hydraulics and engines.
Oil analysis
Lab testing of in-service oil samples to judge oil condition, contamination and machine wear.
Demulsibility
How quickly an oil sheds water and settles into clean layers after being churned with it.