General Info

Poppet Valves - General Info


Bodies are die-formed from 304 stainless steel to eliminate sharp inside corners and improve conductance. The valves are electropolished for faster pumpdown, lower outgassing and better corrosion resistance. The welded bellows are made from AM-350 stainless steel to provide corrosion resistance and excellent flexibility. The bellows fully retract from the side port when the valve is open, eliminating buildup of by-products on the bellows and subsequent particle generation during operation. They are designed with additional segments to provide extended life. Nor-Cal valves can be operated in any position and actuators can be removed quickly for routine inspection without disassembling the system.


Our poppet valves are available in most port configurations with CF, NW, ISO, EVAC or ASA flanges. Valves through 3 inch OD?s are available with manual or pneumatic actuators and Viton or copper bonnet seals. Valves over three inches are available with pneumatic actuators only. Custom port lengths, flange configurations and bellowless valves are also available.

Vacuum Range

Poppet seals have helium leak rates of 10-9 std. cc./sec. or less. Viton bonnet sealed valves can be used in the 10-9 Torr range, while copper bonnet seal valves are suited for use in the 10-10 range.

Valve Actuation

Manually operated valves utilize Acme threads and a self-lubricating bronze nut for fewer turns and smooth, trouble-free operation. Pneumatic valves are normally air-to-open, spring-to-close in port ODs through 2 inches for immediate closure in case of electrical or air failure. Larger valves are normally air-to-open, air-toclose. This actuation option is available on all valves. Most sizes are available with air-to open, air-to-close with spring assist as an option. Operating air pressure for all pneumatic valves is 60 to 80 psig.

Heater Products

All Ebara poppet valves and gate valves can be provided with silicone foam or fiberglass insulated heater jackets to reduce resident time of corrosives or particle buildup in semiconductor applications. These jackets are available with PID controllers or thermostats with high temperature shutoffs. Jacket and control specifications can be tailored to meet your specific needs. Call for price and model number. Refer to Section 11, Thermal Products, for more information.


The valve's bakeout temperature should not exceed that of the elastomer that is used in it. See chart below. Standard Viton sealed valves are bakeable to 150÷C sustained and 204°C for intermittent periods. However, the Viton O-rings begin to take a set at 150°C. High temperature Kalrez O-rings are available as an option and allow these valves to be baked to 220°C for intermittent periods and 170°C for extended periods.

Viton General purpose 150ºC 120ºC 150ºC 100ºC
Kalrez 4079 High temperature 280ºC 220ºC 280ºC 150ºC
Kalrez 2037 Chemical resistant 218ºC 218ºC 218ºC 218ºC
Chemraz Chemical resistant 210ºC 210ºC 210ºC 210ºC
Silicone High temperature 232ºC 232ºC 232ºC 232ºC

Copper Bonnet Seal

Copper bonnet seal poppet valves with CF flanges provide metal seals between the inside of the valve and the atmosphere. They are available in all standard sizes and port configurations.

Poppet Valve Conducatance

The conductance values in the table below have been calculated for air at room temperature using the formulas for tubes and elbows presented in the third edition of Roth's Vacuum Technology: Cv=182(D4/L')P for viscous flow or Cm=12(D3/L') for molecular flow. Port lengths without flanges and inner diameters for the valve sizes and configurations were used. This method is an approximation, use values accordingly.

1/2 60 3 - - 45 2 - -
3/4 135 5 120 4 105 4 90 4
1 391 12 286 9 270 8 - -
1-1/8 - - - - - - 436 11
1-1/2 1925 37 1324 25 1263 24 1203 23
2 4677 65 3459 48 3113 44 - -
2-1/2 12332 136 7505 83 7610 84 - -
3 23263 217 12558 115 14258 130 - -
4 57994 396 - - 34577 236 - -