RPVOT  RBOT 
       The RPVOT (formerly referred to as RBOT) 
       test is a measure of an oil’s ability to resist 
       oxidization.   However, ASTM D2272 advises 
       that the test is not intended to compare one 
       new oil formulation to another:  
       “4.1  The  estimate  of  oxidation  stability  is 
       useful  in  controlling  the  continuity  of  this 
       property for batch acceptance of production 
       lots  having  the  same  operation.  It  is  not 
       intended that this test method be a substitute 
       for Test Method D943 or be used to compare 
       the  service  lives  of  new  oils  of  different 
       compositions.”  
       Oxidization  is  one  of  the  primary  contributors  to  oil  degradation.    The  process  of 
       oxidization produces acids and by-products that form varnish and sludge, coat bearing 
       surfaces, narrow clearances or clog passages, all preventing lubricants from performing 
       effectively. 
       The RPVOT may be used to monitor the depletion of oil antioxidants over time and 
       estimate the oil’s remaining useful life.  Due to the time required and the expense of the 
       tests, it is usually performed on large capacity oil reservoirs (as in steam turbines), on 
       an annual basis.
       The test is performed by placing an oil sample in a a pressure vessel with water and a 
       copper  catalyst,  then  pressurizing  the  vessel  with  pure  oxygen  while  rotating  the 
       sample.  As the antioxidants in the oil react and are consumed by the pressure, rotation 
       and oxygen, the pressure in the vessel begins to drop.   The time it takes for the 
       pressure to drop to the specified end point of the test is recorded in minutes as the 
       RPVOT.