Dual plate check valve – wafer or lug or flange type dual plate check valve

Check valves are automatic in operation and designed to prevent reversal of flow in fluid piping systems. So when the medium is back-going, valve disc will automatically close to avoid accidents. The check valves are maintained open by the flow of fluid in the forward direction and are closed by a spring force, or by the weight of the closing mechanism, or by back pressure of the fluid.

Dual plate check valve , one type check valve, typicaly see with wafer dual plate check valve, lug type dual plate check valve, flanged dual plate check valve, as per connection type, butt weld is very rare. It is also called split disc check valve, butterfly check valve(like a butterfly valve, this type valve has more similar structure with butterfly valve, compare with gate, globe, ball valve), duo disc spring loaded check valve(double disc with spring).

SGV offer dual plate check valve with stainless steel trim, usually CF8, CF8M, CF3,CF3M,(304, 316,304L,316L) Duplex steel, carbon steel disc is available but not suggested, Enconel spring, metal seating, is our noraml combination( with stem, spring, washer, gasket, hex nut and other necessary fittings).

It is designed to overcome the size and pressure drop limitations of the swing and disc type wafer check valves (somebody think dual plate is also swing type check valve ). It has many available types or modes so as to meet the generally complex and specific requirements, both in the industrial process and the daily life.

The disc(two plates)  of dual plate check valves are held against the seat by a torsion spring mounted on the hinge. And the external mounted retainer pins of valve are needed to hold the hinge in the centre of the flow path. Besides, an improved design secures the hinge internally and the valve mechanism is entirely sealed within the body so to prevent out leakages caused by retainer pin effectively.

Usually Applied Standard:

Design and manufacture: API594, API6D, JB/T8937.
Pressure-Temperature grade: ANSIB16,34, DIN2401, GB/T9124, HG20604, HG20605, SH3406, JB/T74, ANSI B16.34                                                                                             Length of structure (face to face,end to end): API594, API6D, DIN3202, JB/T8937             Inspection and test : API598, JB/T9092                                                                             Pipe flange:APIT605,ASMEB16.47,ANSIB16.5,DIN2543~2548,JB/T74~90,GB/T9112/9124, HG20592~20635, SH3406,  GB/T13042,

Check valve-Non-return valves:lift check valve,swing check valve,butterfly check valve,dual plate check vavle,tilting disc check valve

Check Valve
Check valves or Non-return valves (NRV) are normally installed in piping to avoid back flow. Rotating equipment such as pump, compressor, etc will always be equipped with NRV(s) on the discharge to avoid back flow when rotating equipment is shut. Back flow creates severe surging to the rotating equipment and potentially damage the equipment. In certain process system, NRV will be employed to avoid contamination, overheating, etc due to back flow.
Check valves or Non-return valves (NRV) -One way valve is basically an automatic valve open to allow forward flow and close to against reverse flow. In principle, it split into four basic types. There are swing, dual-plate, tilting disc and lifting type. Wrong selection of check valve type can leads to operability problem, leakage and continual maintenance issue.

Lift Check valves

– higher pressure drop is expected.
– equipped with small return spring to facilitate valve closure on reverse flow
– two type of seat. hard seat for for high differential pressure sealing and resilient seat for low differential pressure sealing
– shortest travel length. Fastest response.
– excellent performance for low and/or pulsating flows
– not good for fluid with particles
– Body install horizontal with disc / piston vertically
– Small check valve range from 1/2″ to 2″ lift piston type check valve
– Prefer operate in full open position
Minimum Recommended Line Velocity, Vmin (ft/s) = 12 SQRT (v)
where
v = Specific Volume of the Fluid (ft3/lb)

Swing Check Valve

– Tight sealing / shut-off
– Low pressure drop
– Susceptible to water hammer
– Not good for low flow and/or pulsating flow
– Vertical (upward flow) & horizontal installation
– Easiest check valve to maintain
– Prefer operate in full open position
Swing check valves should be sized such that the flow velocity in the line is sufficient to hold the disc in the fully open position.
Minimum Recommended Line Velocity, Vmin (ft/s) = 75 SQRT(v)
where
v = Specific Volume of the Fluid (ft3/lb)

Dual plate Check valve

The characteristic of dual plate check valve is pretty same as swing check valve.
– low pressure drop
– Not good for low flow and/or pulsating flow
– Vertical (upward flow) & horizontal installation
– Faster opening and closure compare to swing check valve
– Susceptible to water hammer (lesser than Swing check valve)
– Prefer operate in full open position

Tilting Disc Check Valves

– Fast opening and closing without damage to disc and seat
– Stable at low and pulsating flows
– Moderate pressure drop. Lower than lifting check valve but higher than swing check valve
– Vertical (upward) & horizontal installation
– Moderate tight sealing
– Prefer operate in full open position
Minimum Recommended Line Velocity, Vmin (ft/s) = 24 sqrt (v)
where
v = Specific Volume of the Fluid (ft3/lb)

Selection Consideration
There are four (4) main criteria shall be considered for the selection of check valve type :
non-slam characteristic
pressure loss
cost
application
Comparative rating for each type of check valve have been provided for these criteria (specifically first two technical criteria). These rating will be plotted on a Check Valve Comparative Selection Chart and together budget for final selection.

 

Wafer type Dual plate check valve updated

SGV updated it’s product: Wafer type Dual plate check valve

It has many ways of calling, Dual plate, Duo disc, Double disc, Double plate check valve, it is swing type, also a butterfly type check valve, spring loaded to help return quickly. It is a retainerless check valve,  can be lug type, flanged type also. It has wide application by choose suitable material. Can be used for following industry, food, building, oil and gas, pipeline, chemical, petrochemical, waste water, transportation and so on.

More information, contact us