Our online catalog is being updated! Please contact us for current pricing. Valve Specifications and Construction All gate, roughing, and bakeable valves have the following standard specifications. Customers may request other material on special order. "Roughing valves" refers to all inline and angle valves. Although they are designed and built for UHV applications, these valves can be used in roughing applications. Service Life Up to 100,000 closures with standard bellows seal, dependent on bellows type, poppet seal type, and application Special long life bellows available Up to 500,000 closures with O-ring shaft seal Design No trapped volumes or virtual leaks. Valve Construction Thermionics valve bodies are made of 304 stainless steel. All vacuum-exposed surfaces are 300 series stainless steel. They are engineered, manufactured and internally TIG welded, or 100% full penetration TIG welded, to insure elimination of virtual leaks. Before assembly the valve parts are chemically cleaned and polished. Construction Materials VALVE BODY Fabricated from type 304 stainless steel with all internal or back filled full penetration welds using GTAW (known also as TIG) gas welding process. INTERNAL MECHANISMS Fabricated from type 304 stainless steel, fully welded GTAW process. CLEANING Valves are chemically cleaned for vacuum service. BODY SEAL Viton® O-ring or OFE copper captured gasket, depending on model. GATE/POPPET SEAL Viton® O-ring for gate and roughing valves, bakeable valves use an OFE copper gasket. BEARINGS Needle and ball bearings, dry film lubricated. BELLOWS SHAFT SEALS Fabricated from special application 300 series stainless steels. Roughing and bakeable valves use fully nested, welded bellows assemblies, gate valves may use nested welded or hydroformed bellows, with UHV furnace brazed transition pieces. All bellows have additional convolutions for longer operating life. PNEUMATIC ACTUATORS Virgin aluminum cast or drawn. Bakeability Bake-out temperatures are limited by seal material selection, in general: Buna-N 80°C maximum Viton® 250°C valve open/unloaded; 200°C valve closed/loaded Kalrez® 250°C valve open/unloaded; 150°C valve closed/loaded All metal 450°C valve open or closed Solenoids 65°C Leak Free Tested vacuum adverse condition to be leak free with a helium MSLD to a sensitivity of 2 x 10-10 std cc/sec, no detectable leak. Orientation May be mounted in any position. Actuators Manual Actuation: Rotation of the hand knob which is connected to a coarse threaded Acme screw for speedy full opening and closing of valve's poppet seal. Pneumatic Actuation: An air cylinder replaces the hand knob described above and is attached to the valve body flange. The air cylinder consists of an air cylinder shaft that is coupled through the bellows (or an O-ring seal) to the seal poppet shaft and thus to the seal poppet. When air is introduced below the air cylinder piston, the valve opens. When air is introduced above the air cylinder piston, the valve closes. Repair and Replacement: Not only can you remove, repair, and replace the pneumatic actuator without removing the valve from the system, but more importantly, you can do all of this while maintaining the vacuum. Electro-Pneumatic Actuation: Pneumatic valves utilizing a solenoid valve to open or close the valve's seal poppet. The solenoid automatically closes the valve in the event of a power failure, or if the user prefers, it can be engineered to open the valve in the event of a power failure. Solenoid Control Valves: TLI valves with pneumatic actuators are supplied with a 120 VAC, 60 Hz solenoid control valve. We do not charge extra for solenoids like other manufacturers. Because of their limited temperature range, solenoids are not supplied on metal bonnet valves or on spring-actuated valves. They may be ordered separately. Other solenoids are available, including: 12 and 24 VDC, and 24, 100 and 210-240 VAC, 50-60Hz. There is an additional charge of $35.00 for most special solenoid valves. Please consult the factory for current price information and other options. Spring Loaded Actuation: A spring may be added to the pneumatic actuator to either close or open the valve when there is a power failure. The spring will insure that the valve remains in that position as long as the power is off. Air-to-Open/Spring-to-Close Valves: TLI air-to open/spring-to-close valves offer two unique features other valves do not: TLI valves close, using only the spring, even against atmosphere, and are guaranteed to be leak-free. Each valve is leak-checked with a MSLD, and is certified to be leak-free when checked to a sensitivity of 2 x 10-10 standard cc/sec. Each valve is checked in the vacuum adverse condition, using only the spring for closing power, with vacuum pulled on the back side of the sealing poppet and atmosphere trying to force the poppet open. The result? The valve will seal even when both the electrical power and air supply fail. It is slightly more expensive, but it is a superior product offering greater performance. These valves open fully, no portion of the bellows or poppet obstruct the valve port, allowing full conductance. Motorized Actuation: Operated solely by an electric motor. Position Indicators/Limit Switches Most commonly used with pneumatic valves, designed to show if the seal poppet is in a closed or open position. Thermionics offers both magnetically actuated reed switches and positively actuated microswitches. Both can be provided with lights located either at the valve or at a remote location. Flanges All valves are available with flanges of your choice, be they ConFlat type, ISO, ASA, custom, etc. Retention of Gasket in Sealing Poppet An elastomer gasket seal is held in a double dove-tailed groove to insure retention of the gasket when the vacuum seal is broken. This is particularly important after a bake, when pulling away the seal poppet, or gate, from the sealing surface(seat), or when there is a pressure differential across the seal. Choice of Sealing Gasket Your choice of all metal, Viton®, Kalrez®, polyimide, and Teflon® sealed valves. Viton® is the most common sealing gasket material used with the seal poppet or gate. Thermionics offers a wide range of alternative sealing gaskets to users with special bakeout and/or chemical resistance requirements, e.g. copper, Kalrez®, polyimide, Teflon®, Buna-N, aluminum, gold, etc. Viton® is a registered trademark of DuPont Dow Elastomers.