Kittiwake electronic TAN Test .
Info Centre >> Fuel and Lube Oil Technical Manual >> 7. Lube Oil - Test Results >> 7.6 Hydraulic Oil >> 7.6.3 Total Acid Number (TAN)
It should be noted that both the new oil total acid number and the direction of initial change as oxidation progresses may vary between oil products from different suppliers.
Hydraulic oils operate in enclosed systems where exposure to air and therefore oxygen is low. The only interface between air and the surface of the oil is at the system reservoir tank. Oil degradation through oxidation is not therefore generally as much of a problem in a hydraulic oil system as it is in systems that bring the oil into intimate contact with air.