| Gate Valve | Full open or full closed isolation; the wedge or gate moves perpendicular to the flow. | Gray cast iron body Cast iron or coated wedge Stainless steel stem | Flanged; threaded or grooved designs may be available in smaller sizes. | Municipal water distribution, chilled-water lines, fire-protection systems, irrigation and general utility piping. | Low pressure loss when fully open; suitable for large line sizes; simple isolation duty. | Not recommended for throttling; repeated throttling can damage the seating surfaces. Gray cast iron is unsuitable for severe shock, high-impact service and many corrosive fluids. | ASME B16.1 for cast-iron flanges; MSS SP-70 for iron gate valves; EN 1171 for industrial gate valves. | Choose a resilient-seated design for water service where bubble-tight shutoff and lower operating torque are required. |
| Globe Valve | Regulates or throttles flow using a movable disc and a stationary seat. | Gray cast iron body Metal or resilient seat Steel or stainless steel stem | Flanged; screwed ends are used in selected small-size patterns. | Heating-water control, cooling-water balancing, steam or utility services within the approved pressure and temperature range. | Good throttling capability; predictable flow control; easier maintenance than many specialty control valves. | Higher pressure drop than a gate or full-port ball valve; unsuitable for highly abrasive slurries unless specially designed. | ASME B16.1 for flanges; EN 13709 for globe valves; applicable project piping specifications. | Use when regulation is more important than minimum pressure loss. Verify seat, packing and temperature ratings before steam service. |
| Swing Check Valve | Prevents reverse flow with a hinged disc that opens in the forward-flow direction. | Gray cast iron body Cast or ductile iron disc Stainless steel hinge parts | Flanged; wafer or lug connections are more common in butterfly-style check valves. | Water supply, wastewater, pump discharge, cooling-water circuits and low-to-moderate velocity utility lines. | Low pressure loss at adequate flow velocity; automatic operation; no external actuator required. | Can slam when flow reverses quickly; installation orientation and minimum flow velocity are important. Not ideal for pulsating flow. | API 594 for check valves; EN 12334 for industrial check valves; ASME B16.1 for cast-iron flanges. | Confirm allowable installation position, closing characteristics and pump-system surge conditions. |
| Wafer Check Valve | Stops reverse flow with one or two spring-assisted discs positioned between flanges. | Cast iron body Stainless steel disc Elastomer seat | Wafer type installed between pipe flanges. | HVAC water systems, compact pump skids, water treatment, compressed-air utilities and general process water. | Short face-to-face length; low weight; economical for space-limited installations. | Requires correct flange alignment and sufficient flow conditions; disc movement may be affected by pulsating or dirty fluids. | API 594; EN 12334; applicable wafer-valve dimensional requirements. | Select spring material and seat compound according to fluid chemistry, temperature and cycle frequency. |
| Butterfly Valve | Quarter-turn isolation or throttling using a rotating disc. | Cast iron body Ductile iron or stainless disc EPDM, NBR or PTFE seat | Wafer, lug, flanged or grooved. | HVAC chilled and hot water, water treatment, irrigation, fire-protection systems, air handling and low-pressure utility lines. | Compact and lightweight; fast quarter-turn operation; suitable for large diameters; comparatively low installation cost. | Disc remains in the flow path; throttling can create turbulence; elastomer compatibility limits temperature and chemical resistance. | EN 593; API 609; AWWA C504 or AWWA C516 for applicable waterworks designs; ISO 5752 for face-to-face dimensions. | For water service, EPDM is commonly selected; use NBR for suitable oil-containing service and verify the exact compound rating. |
| Plug Valve | Quarter-turn isolation using a cylindrical or conical plug with a flow passage. | Cast iron body Metal or lined plug Elastomer or PTFE sealing | Flanged; threaded connections are used in selected small sizes. | Water and wastewater, low-pressure gas utilities, drain systems and certain non-abrasive process services. | Quick operation; compact flow path; can provide reliable shutoff when the lining and plug materials are correctly matched. | Operating torque may increase with deposits; conventional cast iron is not suitable for high-pressure hydrocarbon or severe chemical service without a specifically qualified design. | API 599 for metal plug valves; EN 137 gost? | Specify lubricated or resilient-seated construction, fluid compatibility and cleaning requirements. |
| Diaphragm Valve | Controls or isolates flow by pressing a flexible diaphragm against a weir or full-bore seat. | Cast iron body Rubber diaphragm Lined wetted surfaces | Flanged; threaded or sanitary configurations depend on the design. | Water treatment, mildly corrosive liquids, slurry-handling utilities and applications requiring separation of the actuator from the process fluid. | Good isolation of internal moving parts from the fluid; suitable for some dirty or mildly abrasive media; low leakage potential. | Diaphragm life depends on temperature, pressure, flexing and chemical compatibility; not normally selected for high-pressure service. | EN 13397 for diaphragm valves; project-specific lining and material requirements. | Prioritize diaphragm compound, lining material, vacuum capability and cycle life over body material alone. |
| Foot Valve | Combines a check valve with a strainer to maintain pump suction prime and prevent reverse drainage. | Cast iron body Cast iron or stainless strainer Elastomer seat | Flanged or threaded suction connection. | Water-intake systems, irrigation pumps, transfer tanks, wells and low-pressure suction piping. | Protects pumps from debris; helps retain liquid in the suction line; automatic operation. | Screen blockage increases suction loss; access for cleaning is essential; not suitable where the suction fluid is highly corrosive without compatible lining. | Manufacturer and project specifications; connection dimensions should match the applicable flange or thread standard. | Size the strainer area to limit pressure loss and provide a removable arrangement for inspection and cleaning. |
| Y-Strainer with Drain | Removes suspended solids from a liquid or gas stream before sensitive equipment or valves. | Cast iron body Stainless or coated screen Gasketed cover | Flanged, threaded or grooved. | Boiler feed auxiliaries, HVAC water circuits, pump protection, compressed air and general utility piping. | Protects control valves, pumps and heat exchangers; drain connection supports maintenance. | It is not a shutoff valve; pressure drop rises as the screen loads; the body and screen must be protected from freezing and excessive differential pressure. | ASME B16.1 for cast-iron flanges; EN 过滤? | Specify mesh or perforation size, allowable pressure drop, clean-screen area and drain arrangement. |