Test equipment :
needed:
For the test 50 g oil and 5 g water are weighing into a sample container. A polished copper coil is put into the oil-water mixture as a catalyst. The sample container is put into a pressure-resistant stainless steel container and screwed with a sealing together. The container is filled with pure oxygen up to 620 kPa and a manometer on top measures permanent the inside pressure.
The pressurised container is rotating with 60 rpm at 150°C. These extreme conditions (oxygen, copper, water and temperature) speed up the oxidation of the test oil. During this process the oil absorbs oxygen and as result the original oxygen pressure decreases. A diagram with the pressure decrease is being recorded. The measurement is over if the inside pressure drops below 175 kPa of the original maximum value. As more time is needed for this process as higher is the oxidation resistance of the oil.
In large circulating lubricating plants like turbines, paper machines or rolling mills, oils are used for years. But also gear oil from wind energy plants and larger hydraulic plants shouldn`t be changed before 20.000 hours. Therefore oxidation stability is essential. Normally the oxidation level is measured by infrared spectroscopy. But this measuring method doesn’t allow reliable inference to oxidation stability respectively usability of the oil.
The RPVOT-Test (Rotating Pressure Vessel Oxidation
Stability Test) informs about the resistant of the origin oil in comparison to the used oil against oxidation under extreme conditions. As result oil drain intervals become better plan able on a long term period.