Dhanvati industries offers oil-sealed rotary high vacuum pumps. These are of oil-immersed, rotary vane type pumps and rotor, with two spring-loaded vanes, is mounted eccentric in the stator body. As the rotor, rotates the vanes sweep the crescent shape, air space twice in each revolution. There is in-built non-return valve which prevents back flow of air. The pump is manufactured from graded material, all moving parts are precisely machined, ground and assembled with close tolerances. This results in increased efficiency and long trouble free operating life. Application: distillation, dehydration and filtration processes; gls lamps; mercury vapour lamps and tubes; exhausting electronic tubes; refrigerator and air-conditioner servicing; freeze drying of foods; vacuum metallurgy; vacuum sublimation; vacuum impregnation; and thin film coating. Accessories: air ballast - a vent pipe introducing air before actual compression which eliminates condensation of the sucked vapour, thereby avoiding contamination of oil; air admittance valve - an electromagnetic solenoid type which admits air into the system as soon as the power supply fails, prevents back-flow of oil to the system; and non-return valve - a rubber diaphragm type, spring loaded valve, which prevents back-flow of oil to the system as soon as pump stops. These cannot be used to hold the vacuum in the system for longer period.
