How does the check valve work?

Check valve refers to the valve that automatically opens and closes the valve flap relying on the flow of the medium itself to prevent the backflow of the medium, also known as check valve, check valve, counterflow valve, and back pressure valve. The check valve is an automatic valve whose main function is to prevent the backflow of the medium, prevent the reversal of the pump and the drive motor, and the discharge of the container medium. The check valve can also be used to feed the auxiliary system where the pressure may rise above the system pressure. The function of this type of valve is to allow the medium to flow in only one direction and to prevent the directional flow. Usually this valve is automatic operation, under the action of fluid pressure flowing in one direction, the valve disc opens; When the fluid flows in the opposite direction, the fluid pressure and the white overlap valve disc act on the valve seat, thus cutting off the flow.

Check valve basic structure

Check valves have an opening pressure, when the pressure of the working medium is greater than the opening pressure of the check valve, the spring is compressed, the check valve flapper is pushed open, and the medium flows smoothly. When the working medium reflow, the medium will press the baffle on the check valve body, the greater the principle of the medium, the tighter the pressure, at this time the baffle completely isolated the entire system, to eliminate the possibility of media reflow.

Structure and working principle of swing check valve

Definition: The disc of the swing check valve is disk-shaped and rotates around the shaft of the valve seat channel. Because the channel in the valve is in a flow line, the flow resistance is smaller than that of the lift check valve. It is suitable for large diameter occasions where the flow rate is low and the flow does not change frequently, and it is not suitable for pulsating flow.

Lift check valve

A check valve with a disc sliding along the vertical center line of the valve body, a lift check valve can only be installed on a horizontal pipe, and a ball can be used on a high pressure small diameter check valve. The body shape of the lift check valve is the same as that of the stop valve (which can be used in common with the stop valve), so its fluid resistance is larger.

Sandwich check valve

A check valve where the disc rotates around a pin in the seat. The disc check valve is simple in structure, can only be installed on the horizontal pipe, and has poor sealing.

The valve body of the sandwich check valve is in the shape of a pinch, compared with the traditional impact absorption check valve, can achieve thin, heavy and heavy, although it is a thin valve body, but it is a multi-functional, high-performance impact absorption check valve with excellent sealing performance.

4. Common faults and treatment methods

1. Valve disc is broken

Preventive measures: use the valve flap for the ductile material of the check valve 2, the medium backflow

Reason: sealing surface damage; Insert impurities prevention method: repair sealing surface and clean impurities, you can prevent backflow.

Five, daily maintenance content

1, after the installation of the application of the check valve, it should be regularly repaired to ensure its normal operation

2. Check whether the sealing surface of the check valve is worn, and repair or replace it according to the situation. 3, check the trapezoidal thread wear of the valve stem and valve stem nut, whether the packing is outdated and invalid, and carry out the necessary replacement.

4. The check valve in operation should be in good condition, the bolts on the flange and support are complete, and the threads are not loose.

5, if the hand wheel is lost, it should be matched in time, and can not be replaced with a adjustable wrench.

6. The packing gland is not allowed to skew or have no pre-tightening gap.

7, if the use of the check valve environment is more harsh, susceptible to rain, snow, dust, sand and other dirt contamination, should be installed for the valve stem protection. 8, the operation of the check valve, avoid beating on it, or support heavy objects.