Check Valve Generally divided into
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Silent check valve
Is able to automatically prevent the flow of fluid back valve. The valve flap of the check valve opens under fluid pressure and the fluid flows from the inlet side to the outlet side. When the inlet side pressure is lower than the outlet side, the valve flap in the fluid pressure, gravity itself and other factors automatically shut down to prevent fluid backflow.
Check valve: generally divided into lift type, swivel type, butterfly and diaphragm type and several other types.
The structure of the lift check valve is generally similar to the cut-off valve, the valve flap along the channel in the line for lifting movements, reliable action, but the fluid resistance is large, suitable for small caliber occasions. Lifting check valve can be straight and vertical two. Straight-through lift check valves can only be installed in the horizontal pipe, and vertical lift check valve is generally installed in the vertical pipe.
The flap of the swivel check valve is used for rotary motion. Its fluid resistance is generally less than the lift check valve, it is suitable for larger caliber occasions. Swing check valve according to the number of discs can be divided into single-swivel, double-flap and multi-flap open three. Single flap check valve is generally suitable for medium caliber occasions. Large diameter pipe selection single flap check valve, in order to reduce the water hammer pressure, it is best to reduce the water hammer pressure slow closing check valve. Double flap open check valve for large and medium diameter pipe. On the folder double flap swing check valve structure is small, light weight, is a fast-growing check valve; multi-valve swing check valve for large diameter pipe.
The butterfly check valve is similar in structure to butterfly valves. Its structure is simple, flow resistance is small, water hammer pressure is also small.
Diaphragm check valve has a variety of structural forms, are used as a diaphragm opening and closing parts, because of its waterproof hammer performance, simple structure, low cost, in recent years, rapid development. However, the use of diaphragm check valve temperature and pressure by the diaphragm material restrictions.
H76-type double-valve open-type check valve water hammer pressure is small, short valve flap stroke, and a spring-assisted closure, closing valve speed
H44 Flange single flap check valve is very large, the valve flap long, requires a longer closing time
H76 type of water hammer pressure only H44 type 1/2 ~ 1/5
Ball-type sewage check valve: the valve body with full-channel structure, with a large flow, the advantages of small resistance. The use of ball to do the disc, for high viscosity, suspended solids industrial and domestic sewage pipe network return valve: check valve: also known as one-way valve or check valve, its role is to prevent the pipeline in the medium back. Water pump off the end of the valve also belong to the check valve class.
