Definition, function and classification of Check Valve

Check Valve Definition:

   Check valve is to rely on the flow of the media itself and automatically open and close the valve flap, used to prevent the media back flow of the valve, also known as check valve, single way valve, counter flow valve, and back pressure valve.

Check valve function:

  Check valve is an automatic valve, its main role is to prevent the media back, to prevent the pump and drive motor revers e, and the container media release. The check valve may also be used on a line in which the supply pressure of the auxiliary system may be increased beyond the system pressure.

Check valve classification:

Check valve according to its structure and installation can be divided into:

1. Swing check valve

   Swing check valve disc was disc-like, rotating around the axis of the valve seat channel for rotary movement, because the valve channel into a streamlined, flow resistance than the lift check valve is small, suitable for low flow and flow Often change the large-caliber occasion, but not suitable for pulsating flow, the sealing performance is less than lift type. Swing check valve is divided into single-valve type, double-valve type and more than three types, these three forms are mainly divided by the valve caliber, the purpose is to prevent the media stop flow or back flow, weakening the hydraulic shock.

2. Lift check valve

   The valve flap sliding along the vertical center line of the valve, the lift check valve can only be installed in the horizontal pipeline, high-pressure small-caliber valve check valve can be used on the ball. Lift check valve valve body shape and the same (with the cut-off valve common), so it's fluid resistance coefficient. The structure and cut-off valve is similar to the valve body and the valve with the same stop valve. The upper part of the valve flap and the lower part of the valve cover are processed with a guide sleeve. The valve flap can be freely lifted and lowered in the valve guide. When the medium is downstream, the valve flap is opened by the medium thrust. When the medium stops flowing, Dropping down on the valve seat, from the media to prevent backwash effect. The direction of the medium inlet and outlet channel is perpendicular to the direction of the valve seat channel. The vertical lift check valve has the same direction of the media inlet and outlet channel as the valve seat channel, and its flow resistance is smaller than that of the straight-through type.

3. Butterfly type check valve

   A check valve that rotates about a pin in a valve seat. Disc check valve is simple, can only be installed in the horizontal pipe, sealing poor.

4. Pipe-type check valve

   A valve that slides along the center line of a valve body. Pipeline check valve is an emerging valve, its small size, light weight, processing technology is good, is one of the development direction of the check valve. But the fluid drag coefficient is slightly larger than the swing check valve.

5. Pressure-type check valve

This valve is used as a boiler feed water and steam cut off valve, it has a lift check valve and stop valve or angle valve integrated function.