Swing Check Valve type Ball Check Valve Method of erection Plastic Check Valve Structural classification

Check valve is a valve for a circular valve valve and by its own weight and medium pressure action to block the flow of medium backflow. Belongs to automatic valve class, also known as check valve, check valve, return valve or isolation valve. Valve flap movement mode is divided into lifting type and swing type. The lifting check valve is similar to the stop valve structure, lacking only the stem to drive the valve valve. Media flows from the inlet (bottom) and from the exit (top). The valve is opened when the inlet pressure is greater than the sum of the flap weight and its flow resistance. Otherwise, the valve is closed when the medium is reversed. The swing check valve has a diagonal valve flap and rotates around the axis, working in a similar principle to the lifting check valve. Plastic Check Valve is often used as the bottom valve of the pumping device, which can prevent the water reflux. Check valve and stop valve combination, can play the role of safety isolation. The disadvantage is large resistance, poor sealing when closing.

The check valve belongs to this type of valve, which includes rotary check valve and lift check valve. The swing check valve has a hinge mechanism, and a door-like flap that is free against the surface of the tilted seat. To ensure that the flap reaches the proper position on the seat face each time, the flap is designed at the hinge mechanism so that the flap has sufficient room for rotation and has a genuine and full contact with the seat. The flap can be either made all out of metal, or inlaid with leather, rubber, or with a synthetic covering, depending on the performance requirements. When the swing check valve is fully open, the fluid pressure is almost unimpeded, so the pressure drop passing through the valve is relatively small. The flap of the lift check valve sits on the seat sealing face on the valve body. This valve except that the rest of the valve is like the stop valve, the fluid pressure raises the valve flap from the valve seat sealing surface, the medium reflux causes the valve flap to fall back to the valve seat, and cut off the flow. Depending on the conditions of use, the flap can be an all-metal structure or in the form of a rubber pad or rubber ring inlaid on the valve holder. Like the stop valve, the passage through the fluid is narrow, so the pressure drop through the lift valve is larger than the lift valve, and the flow is less limited. The opening and closing part opens or closes by the force of the medium flow to prevent the backflow of the medium. The valve is called the check valve. Check valve belongs to the automatic valve class, mainly used in the pipeline of one-way flow of the medium, and only allows the medium to flow in one direction, so order to prevent accidents.

Structural classification: According to the structure, it can be divided into three types: lifting check valve, rotary check valve and butterfly check valve: 1. Lift check valve are divided into vertical and horizontal types. 2. Spinning check valves are divided into single, double and multi-valve. 3. Butterfly check valve is straight-through. The above check valves can be divided into threaded connection, flange connection, welding connection and clip connection.

Material classification: 1. Cast-iron check valve 2. Brass check valve 3. Stainless steel check valve 4. Carbon steel check valve 5. Forging steel check valve functional classification 1.DRVZ silent check valve 2.DRVG Stainless steel check valve Silent check valve 3.NRVR silent check valve 4.SFCV rubber flap reverse check valve DDCV double valve valve.

Method of erection: 1. rotary check valve: rotary check valve disc disc, around the seat channel of the rotating movement, because the channel in the valve is streamlined, flow resistance is smaller than lifting check valve, suitable for low flow rate and flow is not often change large caliber occasions, but should not be used for pulsating flow, its sealing performance is less than the lifting type. The rotary start type check valve is divided into single flap valve, double flap valve and multiple half valve three, these three forms are mainly divided according to the diameter of the valve, and the purpose is to prevent the medium to stop flowing or backflow, weaken the hydraulic impact. 2. the lift check valve: the check valve of the valve valve along the vertical centerline of the valve body, the lift check valve can only be installed on the horizontal pipe, in the high pressure small diameter check valve valve can be used ball. Ball check valve body of the lifting check valve is the same in shape as the stop valve (in common with the stop valve), so its fluid resistance coefficient is large.

Silent check valve: The upper part of the valve flap and the lower part of the valve cover processing guide sleeve simple, the valve flap guide simple can be freely lifted in the valve flap guide simple, when the medium is along the current, the valve flap opens by the thrust of the medium, when the medium stops the flow, the valve disc falls on the valve seat, to prevent the reverse flow of the medium. The inlet and outlet channel of the medium medium is perpendicular to the valve seat channel; the vertical lift check valve has the same direction as the valve seat channel, and the flow resistance is smaller than that of the direct seat channel. 3. Disish check valve: a check valve where the valve flap rotates around the pin shaft in the valve seat. The disc check valve structure is simple, can only be installed on the horizontal pipe, poor sealing. 4. Pipe check valve: the valve valve sliding along the centerline of the valve body. Pipe type check valve is a new kind of valve, its small volume, light weight, good processing technology, is one of the development direction of check valve. However, the fluid resistance coefficient is slightly larger than the rotary start check valve. Five, compression check valve: this valve is used as a boiler water supply water and steam cut-off valve, it has the lift check valve and stop valve or corner valve comprehensive function.

In addition, there are some check valves unsuitable for pump outlet installation, such as bottom valve, spring type, Y type, etc.