ASTM D3427 Air Release Properties
In hydraulic fluids, engine oils and other lubricating oils prone to mechanical agitation, tiny air bubbles may become entrained during use. This may decrease the fluid’s viscosity, bulk modulus and thermal conductivity and increase its cavitation, compressibility and rate of oxidation, potentially lessening its effectiveness and putting components at an increased risk of thermal, chemical and mechanical damage. Once air becomes entrained, it may dissipate out of the fluid. The more rapidly the air dissipates, the quicker the fluids properties will return to normal. This test measures the time it takes for a fluid to release entrained air at 25°C, 50°C or 75°C.
The sample is heated to the test temperature and the density is determined. Using a specialized apparatus, compressed air is bubbled through the oil for the test time. The time it takes for the sample to return to within 0.2% of the initial density is determined and reported in minutes.
Specify temperature, 25, 50 or 75°C