AAP Industries Resilient Seat Flanged Swing Check Valve (Table E)

Check Valves and Strainers

Swing Check Valves

Swing Check valves are used where the flow moves through the valve in approximately a straight line similar to that in a gate valve, is commonly used in pipe line conveying liquids by gravity or pumping. The check mechanism of the design incorporates a disc which swings on a hinge.

Ball Check Valves

This valve is used where full uninterrupted flow is required. The design of the valve incorporates a compartment for when the fluid is pumped through the valves the EPDM incapsulated steel ball is pushed into this compartment and held there whilst the up steam pressure is applied. When the pump is turned off the ball falls from its compartment and with backpressure assists drops back into the flow path and blocks any return of fluid back to the pump.

Lift Check Valves

A lift-check valve in which the disc, sometimes called a lift, can be lifted up off its seat by higher pressure of inlet or upstream fluid to allow flow to the outlet or downstream side. A guide keeps motion of the disc on a vertical line, so the valve can later reseat properly. When the pressure is no longer higher, gravity or higher downstream pressure will cause the disc to lower onto its seat, shutting the valve to stop reverse flow. Both wafer and piston checks are examples of a Lift Check Valve.

‘Y’ Type Strainers

Y type strainers are designed for inline protection of control equipment, instruments, pumps and regulators. There function is simplistic with fluid passing through the perforated stainless steel sheet, or wire mesh basket which is housed in a Y shaped body made of various materials, brass, steel, cast iron, stainless steel etc. The basket traps the fines and the solids which fall into the leg of the housing. They can be flushed out while the plant is in operation with a ball valve fitted to the leg of the housing, or the basket can be removed completely for cleaning whilst the plant is not operational.