Diffusion Pump OIL (DC-704 ) web66 DC 704 Dow Corning Silicone Fluid DOW CORNINGR 704 diffusion pump fluid is a single component, colorless fluid for high vacuums of 10-6 torr (untrapped) to 10-8 torr (trapped). It performs well in tough, rugged applications and offers quick pumpdowns, even after exposure to air at operating temperatures. It is thermally and chemically stable allowing it to keep pump jets free of tars and hard carbon. It is resistant to oxidation, radiation, and explosion and produces low ultimate vacuums while maintaining relatively high boiler pressure and throughput. DOW CORNING 704 diffusion pump fluid is used to produce high vacuums for the aerospace and electronic industries, for metallurgical and research needs and for certain special vacuum coating applications.