The Savant VPOF 110 is a recirculating oil filter. If you are drying down samples that are in acid, it is a good idea to put a VPOF110 on the High Vacuum Oil Pump. The VPOF110 circulates the pump oil through an activated alumina cartridge which removes the acid from the oil to prolong the life of the pump and reduce the frequency of oil changes.  This will dramatically increase the life of the pump as well.