These Agilent Varian turbo purge valves have a fixed 10 SCCM flow rate, a 1/4 Swagelok gas supply fitting, and are designed to work with most medium sized turbomolecular vacuum pumps which have an M12 vent port thread. Please see the second and third photos of the vent port and cartoon showing installation, instructions are also shown in the TwisTorr 305 FS manual on page 247. The gas purge valve is a protection device to protect the pump bearings against particulate and corrosive gases that could move into the pump. Every valve is made with a thin calibrate sapphire orifice mounted into a cartridge to provide a precise small leak rate, with two special PTFE membranes on each tube side. This is to avoid any particulate, powder and any liquid to come into and occlude the thin hole. Each version of the valve is suited for a particular application: - the Small leak (~ 10 sccm at 1000 mbar) for mild corrosive operation when the partial pressure of the corrosive gas is maximum 10-5 mbar (analytical instruments, ion implanters); - the Large leak (~ 20 sccm at 1000 mbar) for heavy corrosive operations (etching, CVD), when the partial pressure of the corrosive gas is >10-5 mbar. If you wish to use a different flowrate, you might change the supply pressure. For a given supply pressure, the gas purge valve can give you a fixed flowrate value. Please note that the flow amount does not depend on the vacuum side pressure of the valve. These turbo purge valves have Agilent Varian part number PN 969-9240.

Works with the following Agilent Varian turbo pumps:

• TwisTorr 74 FS
• TwisTorr 84 FS
• TwisTorr 305 FS
• TwisTorr 305-IC
• TwisTorr 404 FS
• TwisTorr 704 FS
• TwisTorr 804 FS
• Turbo-V 1001