Wednesday, May 30, 2007


Conventional Swing Check Valve.  Disc Closes through a long 90 degree arc  with reverse flow started. Shut off  characteristics are greatly improved with  addition of outside lever spring or weight  or air cushion chamber. SWING CHECK (SINGLE DISC)
Swing Check shut off depends on gravity (weight of disc) and reverse flow. The pivot point of the swing check is outside the periphery of the disc and, the greater the head, the greater the possibility that the fluid will flow back through the valve before the disc can shut off. To effect complete shut off, the disc of a swing check valve must travel through a 90 angle arc to the valve seat, as shown in Fig. 1. Without resistance to slow the disc's downward thrust, and encouraged by reverse flow, the shut off results in slamming and damaging water hammer. Use caution applying this type check valve where velocities exceed 3 FPS reverse flow and 30 psi.

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