1. n. [Drilling Fluids]
The lowest temperature at which application of a flame to the test chamber of a tester causes vapors of the sample in the chamber to ignite. The test can be applied to base fluids being considered for use in an oil mud or a synthetic mud or to any flammable liquid to determine at what temperature an explosion hazard exists. Test methods, established by API and ASTM, include open-cup and closed-cup tests.
See: API, ASTM, IP, oil mud, synthetic-base mud