Check Valve Types and Installation Best Practices

Function of Check Valves

Check valves prevent backflow automatically without manual or actuator operation. They protect pumps, compressors, and process equipment from reverse flow damage and contamination.

Common Check Valve Types

• Swing check: simple, low-pressure-drop, best for horizontal lines

• Lift check (piston check): for vertical upward flow, quick-closing

• Dual-plate (wafer check): compact, spring-loaded, fast response

• Ball check: for viscous fluids and slurries, clog-resistant

• Tilting disc check: low cracking pressure, large diameter pipelines

• Nozzle check: minimum slam, compressor discharge applications

Water Hammer and Check Valve Slam

Slow-closing swing checks in high-velocity systems cause severe water hammer when flow reverses before the disc closes. Spring-assisted or dual-plate designs close before flow reverses, eliminating slam and associated pressure surges.

Correct Installation Orientation

• Swing checks: horizontal preferred, avoid vertical downward flow

• Lift checks: vertical upward flow only, or horizontal with flow-up orientation

• Dual-plate wafer checks: any orientation if spring-assisted

• Follow manufacturer arrow on body for flow direction

Minimum Straight Run Requirements

Disturbed flow upstream of a check valve causes unstable disc flutter and premature wear. Install check valves at least 5–10 pipe diameters downstream of elbows, reducers, or control valves to ensure stable approach flow.