One of the earliest known identifiers of an oil?s physical properties is its flash point. References to the test, associated with lamp oils, date back to the mid 19th century. In Augustus H. Gill?s seminal text ?A Short Handbook on Oil Analysis? (1898) seven pages were dedicated to describing the different instruments, procedures, and applications of flash point testing. Surprisingly, the common open-cup and closed-cup testers of today were already well established practices over 100 years ago (Figure 1).
Like viscosity, the flash point test has always been a standard part of a lubricant?s specification. And, because of its low cost, simplicity and versatility, the test is popular among the used oil analysis community as well. Most commonly used as a quick pass/fail test for fuel dilution, more applications have surfaced in recent years. The lab analyst can deploy information about a used oil?s flash point to troubleshoot such problems as thermal failure, gamma radiation, solvent contamination, mixed (or wrong) oils, and antifreeze contamination