HomeValve ComparisonsCheck Valve Types Compared: Swing vs Dual Plate vs Lift vs Wafer

Valve Comparison Guide

Check Valve Types Compared: Swing vs Dual Plate vs Lift vs Wafer

Compare all check valve types: swing, dual plate, lift, spring-loaded, and foot valves. Pressure drop, slam risk, installation, and application guide. API 594, 6D, AWWA.

Overview

Swing Check Valve

The swing check valve has a disc that hinges at the top and swings freely open under forward flow and swings shut when flow stops or reverses. It is the simplest, most common non-return valve design, and the lowest pressure-drop check valve in the fully open position.

DN50–DN1200, Class 150–600, WCB/ductile iron, API 6D / AWWA C508

Dual Plate Check Valve

The dual plate (double-door, split disc) check valve has two spring-loaded half-disc plates that close quickly from the centre outward when flow stops. The spring-assisted fast closure minimises backflow and eliminates slam in most applications — making it the preferred design for pump protection.

DN50–DN900, Class 150–600, WCB/SS316, API 594, spring-assisted

Pros & Cons

Swing Check Valve

Lowest pressure drop when fully open — disc swings clear of flow path
Simple design — minimal parts, long service life, field-repairable
Handles slurry, fibrous and viscous media better than lift checks
No springs to fatigue or fail — suitable for low-frequency duty
Lowest cost of all check valve types
Water hammer risk on fast pump trip — disc slams if flow reversal is fast
Not suitable for vertical upward flow (disc does not close reliably)
Chattering at low flow — disc flaps in the partial open position at low velocity
Slow closing speed leads to backflow before disc seats

Dual Plate Check Valve

Fast spring-assisted closing — prevents slam by closing before reversal
Compact wafer body — much lighter and shorter face-to-face than swing check
Suitable for vertical and horizontal installation
Low pressure drop — fully open discs lie parallel to flow
API 594 wafer pattern fits between standard pipe flanges
Spring fatigue at high cycling frequency (>100 cycles/day)
Not suitable for fibrous or slurry media — disc edges can catch fibres
Field repair not possible — replace as unit
Higher cost than swing check at equivalent size

Swing Check Valve vs Dual Plate Check Valve — Specification Comparison

ParameterSwing Check ValveDual Plate Check Valve
Closing MechanismGravity + reverse flow pressureSpring-assisted fast closure
Slam RiskHigh — slow closing allows significant backflowLow — spring closes disc before reversal develops
InstallationHorizontal only (standard)Horizontal and vertical upward flow
Pressure DropVery low — disc swings out of flow pathLow — discs open flat in flow direction
Slurry/Fibrous MediaGood — simple open disc handles solidsPoor — spring mechanism catches fibres
Face-to-Face LengthLong — full flanged bodyShort — wafer body between flanges
Field RepairYes — replace disc and hinge pinLimited — typically replaced as unit
Frequency of OperationLow — no spring fatigueHigh frequency acceptable (spring designed for this)
API StandardAPI 6D, AWWA C508API 594 (wafer pattern)
Typical CostLowestModerate
Sewage ServiceYes — rubber flap versions standardNot recommended
Size RangeDN50–DN1200DN50–DN900

When to Use Each

Use Swing Check Valve when:

Horizontal pump discharge mains where slam is manageable
Large-bore water transmission mains (DN200+)
Sewage and wastewater pump stations (rubber-flap versions for solids)
Low-frequency duty where infrequent reversal makes slam acceptable

Use Dual Plate Check Valve when:

Pump station discharge where water hammer prevention is critical
Vertical pump discharge with upward flow
Desalination and RO plant pump protection
HVAC and building services pump systems (compact installation)

Decision Guide

Choose swing check valves when: (1) pressure drop must be minimised on large-bore water mains; (2) slurry, sewage, or fibrous media is present; (3) simple repair and long life without springs is valued. Choose dual plate check valves when: (1) water hammer prevention is the primary concern (pump stations, desalination); (2) vertical upward flow installation is required; (3) compact face-to-face length is needed. For high-pressure oil & gas service: both types are available to API 6D; select based on flow direction, operating frequency, and water hammer analysis results. For pump protection: dual plate is almost always preferred.

Frequently Asked Questions

What causes check valve water hammer and how do I prevent it?
Check valve water hammer occurs when the check valve disc closes suddenly under high reverse flow velocity, creating a pressure spike (water hammer wave). The main cause is slow disc closure — the pump trips, flow decelerates but the check valve stays open; when reverse flow builds up, the disc slams shut. Prevention: (1) Use a spring-assisted dual plate or non-slam check valve — the spring closes the disc before significant reverse flow develops; (2) Install a surge vessel (air/bladder accumulator) on the pump discharge to absorb the pressure wave; (3) Fit a dashpot (hydraulic damper) to the check valve to slow the last 10–20° of closure; (4) Properly size the check valve — an oversized check valve chatters and slams repeatedly at partial flow.
Can I install a swing check valve in a vertical pipe?
Standard swing check valves cannot be installed in vertical flow because the disc relies on gravity to return to the closed position. In vertical piping, gravity acts on the hinge rather than closing the disc. However: (1) In vertical upward flow — the disc is pushed open by upward flow and falls closed when flow stops (gravity closes it) — this is acceptable for standard swing checks but has poor sealing at low back pressure; (2) In vertical downward flow — the disc stays open by gravity and reverse flow must push it closed — not recommended, unreliable closure. For vertical upward flow: dual plate check valves (spring-assisted) are the correct choice. For vertical downward flow: lift check valves (piston type) work reliably.
What is the difference between API 594 and API 6D for check valves?
API 594 covers wafer and wafer-lug check valves — it defines the short face-to-face dimensions for check valves that fit between standard pipe flanges (no integral flanges). API 594 check valves are the dual plate and lift (piston) designs used in process and pump service. API 6D covers pipeline valves including swing check valves with full integral flanges on the body (flanged ends), designed for pipeline and pigging service. API 6D check valves have a longer face-to-face dimension (per API 6D Table 1) and are built for higher pressure classes and pipeline operations where full-body structural integrity is required. For process plant pump discharge: API 594 dual plate. For pipeline main line non-return: API 6D swing or tilting disc check valve.

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