Machinery Lubrication


Machinery Lubrication magazine published by Noria Corporation

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54 | September - October 2017 | O i l A n a l y s i s number of testing methods can be used to determine the per formance charac- teristics of a lubricating oil. Two common tests that have endured over time are flash point and volatility. Although the methods, technology and practices have changed through the years, both of these tests are still utilized today and provide viable ways to assess new and used oils. Flash Point The flash point test dates back to the mid-19th century as one of the earliest iden- tifiers of an oil's physical properties. It was originally used to determine the fire hazards of fuels and oils being stored and transported. The f lash point test measures the tendency of an oil to form a flammable mixture with air. Once the oil sample is heated, a flame is exposed to the headspace. Ignition is the determining point. The lowest measured temperature at which the oil will ignite or flash is recorded as its flash point. If the test is performed over a longer period of time, the oil's fire point can be obtained. The fire point is when ignition is sustained for five seconds. Several methods can be employed to determine an oil's flash point. Each varies depending on the fluid's viscosity and the chosen technique. Among the ASTM tests that are available include ASTM D56, Flash Point by Tag Closed Cup Tester. It is utilized for viscosities below 5.5 centistokes (cSt) at 40 degrees C (104 degrees F), as well as for viscosities below 9.5 cSt at 25 degrees C (77 degrees F) and flash points below 93 degrees C (220 degrees F). ASTM D93, Flash Point by Pensky-Martens Closed Cup Tester, is used for petroleum prod- ucts with a temperature range of 40 to 360 degrees C (104 to 680 degrees F) and biodiesel with a temperature range of 60 to 190 degrees C (140 to 374 degrees F). ASTM D92, Flash and Fire Points by Cleve- land Open Cup, is another option for obtaining an oil's flash point. Although the technology has evolved, the open and closed cup tests of today closely resemble the practices of more than 100 years ago. While often seen as a FLASH POINT: A VOLATILITY What You Should Know VS. BACK PAGE BASICS G a rre t t Ba pp | Nori a Corpor at ioN

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