INTRODUCTION

  • The dual Plate Check Valve is an all-purpose non return valve that is much stronger, lighter in weight and smaller in size compared to a conventional swing check valve.
  • The Dual Plate Check Valve employs two spring-loaded plates hinged on a central hinge pin.
  • When the flow decreases, the plates close by torsion spring action without requiring reverse flow.
  • Dual Plate Check Valve comes in 3 types of design mainly in Lugged, Wafer and Flanged type.
  • For all 3 types of Dual Plate Check Valves, the size ranges are from 2” to 32” with a pressure rating class of 150# to 2500#.

TYPES OF DUAL PLATE CHECK VALVE

WAFER TYPE

Wafer type Dual Plate Check Valves are mounted between flanges, without any flange on the valve itself of any type or ears with threads for bolts.

They are sandwiched between the flanges on the ends two lengths of pipe. To replace either length of pipe requires shutting the system down.

LUGGED TYPE

A lugged type will have threaded holes for normally all bolts.

Mono-flange valve could also have a brim with unthreaded holes.

FLANGED TYPE

Flanged-end valves are easy to install or remove from a pipeline, being bolted to the mating pipe flanges.

To ensure a tight seal, a gasket is usually fitted between the machined facing of the flanges.

The type of gasket, which can be non-metallic, metallic or a combination of both, depends upon service conditions and upon the type of flange facing employed.

OPERATION

  • The plate are smaller in area and lighter in weight being two in number compared to one in a conventional swing check valve.
  • The unique feature of plate opening where, it first lifts up at heel and then swings ensures no rubbing actions against seat.
  • This result in lower rate of wear and tear of seals this feature is not feasible in other designs which results in a higher rate of seal wear. This is achieved by the special spring action and hinge design.

  • To eliminate fluid hammer, a Check Valve should close without any reverse flow.
  • Fluid hammer is almost not exists since closing of the valve does not depend on back pressure and back flow.
  • Each plate being half the size of a swing check disc therefore, it can pass through the process flow more easily and quickly.
  • Due to spring assisted closing, valve closure starts as soon as flow velocity reduces below the designed minimum velocity and thereafter the closing rate follows the flow velocity pattern.
  • Hence, the valve closes as the flow velocity reduces to zero, before the flow reverses, thus eliminating the water hammer.

APPLICATION

Some of the typical applications are water supply systems, fire water systems, cooling water, chilled /hot water systems, boiler feed water, sea water, drinking water, and raw water.