Selection of valves for vacuum systems

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Selection of valves for vacuum systems – Control valves for pipelines with a diameter of DN65 or less: Ball valves: The cold operating pressure for such valves should be 600 psi. They feature a two-piece cast bronze valve body, PTFE valve seats, standard flow channels, separately packaged nuts, an adjustable valve stem packing, a design to prevent the valve stem from being blown out, and chrome-plated brass/bronze ball bodies. In areas where pressure drop needs to be controlled, ball valves with full flow passages that do not reduce diameter or valves with similar designs should be used. The valve connection ports shall have ANSI threads of sufficient depth, in accordance with the American Standard Association standards, or extended welded ports, and shall be manufactured in compliance with the MSS-SP110 standard issued by the American Society of Manufacturers of Valves and Fittings. Standard flow channel valve that can be used: American Nibco T-580-70 ball valve (threaded) ； S-580-70 ball valve (welded): Available reduced-bore full-flow valves include the American Nibco T-585-70 ball valve (threaded) ； S-585-70 Ball Valve (Welded) Check Valve: Check valves with a diameter of DN65 or less should adopt a Y-type swing mechanism and be manufactured in accordance with the MSS-SP80 standard issued by the American Society of Valve and Pipe Fitters Manufacturers. They are designed for a working pressure of 125 pounds, have bronze valve bodies that comply with the ASTM B 62 standard, and are equipped with polytetrafluoroethylene seat valve discs, or they can be spring-driven lift type check valves with elastic seats. The valve connection method should be threaded or welded. Available valves: 125-pound American Nipco T-413-Y check valve (threaded) ； S-413-Y (welded) American Nibco T-480-Y spring-driven lift type check valve (threaded) ； S-480-Y (Welded) Line control valves for pipelines with a diameter of DN65 and above – Butterfly valves: These valves should have lug-type or I.P.S. tubular connection port valve bodies, and be manufactured in accordance with the MSS-SP67 standard issued by the American Society of Standardization for Valve and Fitting Manufacturers ； For pipe diameters ranging from DN50 to DN300, the rated operating pressure is 200 psi for non-impact cold water; for diameters larger than DN350, it is 150 psi. The valve body used for thermal insulation has an extended diameter of 2 inches, and is made of cast iron or ductile iron. The butterfly plate is made of electroplated ductile iron or aluminum bronze alloy, and is equipped with Dinar rubber-N seat seals ； Or butyl rubber-N coated disc, with a polymer-coated valve body. The valve stem should be made of 400 series stainless steel, and the valve stem must not be exposed to the butterfly plate fasteners. For pipe diameters from DN65 to DN150, an operating handle equipped with 10-position throttle plates should be used ； Butterfly valves with a diameter of DN200 or larger should be equipped with a gear-operated actuator. Lug-type and tubular butterfly valves should be able to be used as isolation valves, and can also be used at the end of pipelines at full pressure without the need for a downstream flange. Levers for operating valves should be suitable for locking in the open or closed position. Available valves: Nippon Valve LD3110-3 butterfly valve with luged valve body and electroplated ductile iron butterfly disc (handle-operated actuator) ； LD3110-5 butterfly valve (gear actuation mechanism), flanged valve body, aluminum bronze butterfly disc; American Nibco LD2100-3 butterfly valve (handle actuation mechanism) ； LD2100-5 butterfly valve (gear actuation mechanism), tubular valve body with rubber-coated butterfly disc; American Nibco GD4775-3 butterfly valve (handle actuation mechanism) ； GD4775-5 Butterfly Valve (Gear Operated) Check Valve: Check valves with a diameter of DN65 or larger should have a flat-type (clamp-type) structure, be equipped with stainless steel springs, bronze valve disc plates, and rubber seat; the valve body shall be made of cast iron that meets ASTM A 126 Grade B or A 48 standards, and it should be fitted with 125-pound or 150-pound class flanges. Available valves: American Nibco W-920-W, KW-900-W, or W-910-W spring-driven lift-type check valves