Check Valve Selection: Swing, Lift, Dual-Plate and Axial Types Compared
Quick Answer
- Check valves prevent backflow; selection is governed by flow direction, installation orientation, and water-hammer risk.
- Swing check: large bore, low pressure loss, but noisy closure (water hammer) — pair with a slow-close device for pumps.
- Lift check: small bore, tight sealing, horizontal install only (spring-loaded can be vertical).
- Dual-plate (wafer): compact, light, fast spring-assisted closure, low water hammer — space-limited and large-bore up to DN600.
- Axial (venturi) check: lowest pressure loss, best for anti-surge and critical pump discharge.
- Foot valve: at pump suction, keeps the prime.
How a Check Valve Works
A check valve is a passive, self-actuating valve that permits flow in one direction and automatically blocks reverse flow. It has no operator; the disc opens under forward pressure and closes by gravity, spring force, or backflow.
Types and Selection
| Type | Mechanism | Advantages | Disadvantages | Typical use |
|---|---|---|---|---|
| Swing | Hinged disc rotates | Low pressure loss, economical at large DN | Water hammer on close, horizontal install | Pump discharge DN≥50, mains |
| Lift | Disc rises in guide | Tight seal, fast close | Higher pressure loss, clean media | Small bore DN15–100, steam, oil |
| Dual-plate (wafer) | Two spring half-discs | Compact, light, low water hammer | Slight leakage > single swing | DN50–600 water/air; space-limited |
| Axial (venturi) | Disc slides on axis | Lowest loss, minimal surge | Higher cost | Critical pump discharge, anti-surge |
| Foot | Swing + strainer at suction | Holds prime | Added suction resistance | Pump suction bottom |
| Silent / slow-close | Buffer or damper | Low noise, low water hammer | More complex | High-rise water, building services |
Selection by Scenario
| Location | Recommended | Reason |
|---|---|---|
| Pump discharge (prevent reverse spin) | Swing (DN≤150) or dual-plate / axial (large) with slow-close | Stops reverse flow on trip; large bore picks dual-plate/axial to cut water hammer |
| Pump suction | Foot valve with strainer | Keeps suction line primed |
| Small branch (DN≤80) | Spring-loaded lift | Compact, fast close |
| Steam line | Swing, metal-seated | Soft seat unusable at high temp |
| Fire ring main nodes | Swing or dual-plate | Match system pressure class, accessible |
Key Parameters
- Cracking pressure: swing/dual-plate ~0.02–0.05 MPa; spring-loaded types are adjustable.
- Flow velocity: too low may not open swing/lift reliably; too high increases drop, wear, and water-hammer.
- Direction: the arrow must match flow; wrong orientation prevents opening or sealing.
- Media cleanliness: slurry or high-viscosity fluids (heavy oil, syrup) → dual-plate, ball, or non-slam type to avoid sticking; avoid lift/swing.
Water Hammer and Check Valves
A swing check snaps shut and can induce water hammer on pump trip. Mitigate with slow-close (hydraulic) check valves, dual-plate, or axial designs. See the water hammer prevention guide for surge details, and the valve troubleshooting guide for leakage diagnosis.
Use ValveSpecs Pro to filter by type and pressure class. For the broader picture see the complete valve selection guide.
FAQ
How do I choose between a swing and a lift check valve?
Use a swing check for large-bore, low-loss, horizontal lines (pump discharge, mains). Use a lift check for small-bore, tight-sealing duty; it is horizontal-only unless spring-loaded (then vertical is possible).
What causes check valve water hammer?
Sudden disc slam on reverse flow — most acute with swing checks. Mitigate with slow-close (hydraulic), dual-plate, or axial designs that close gradually.
Can a check valve be installed vertically?
A swing check works vertically only if flow is upward. A lift check needs to be spring-loaded for vertical service. Dual-plate and axial designs accept vertical installation.
Which check valve is best for slurry?
Dual-plate, ball, or non-slam types resist clogging. Avoid lift and swing checks, whose guided discs and seats trap solids and wear quickly.
Frequently Asked Questions
How do I choose between a swing and a lift check valve?
Use a swing check for large-bore, low-loss, horizontal lines such as pump discharge and mains. Use a lift check for small-bore, tight-sealing duty; it is horizontal-only unless spring-loaded, which allows vertical installation.
What causes check valve water hammer?
Sudden disc slam on reverse flow, most acute with swing checks. Mitigate with slow-close hydraulic, dual-plate, or axial designs that close gradually and dissipate surge energy.
Can a check valve be installed vertically?
A swing check works vertically only if flow is upward. A lift check needs to be spring-loaded for vertical service. Dual-plate and axial designs accept vertical installation.
Which check valve is best for slurry?
Dual-plate, ball, or non-slam types resist clogging from suspended solids. Avoid lift and swing checks, whose guided discs and seats trap solids and wear quickly.