Views:129 Author:Site Editor Publish Time: 2017-12-19 Origin:Site
A one-way valve is a flow of fluid only along the inlet, and the outlet medium can not flow back, commonly known as a one-way valve.The one-way valve is also called check valve or non return valve.It is used in hydraulic system to prevent the flow of oil flow, or to prevent the reverse flow of compressed air in the pneumatic system.One-way valves have direct and rectangular types.Straight-through one-way valve is installed on the pipe by threaded connection.Rectangular one-way valve has thread connection, plate connection and flange connection three forms.
The one-way valve is also called the check valve or non-return valve.It is used in hydraulic system to prevent the flow of oil flow, or to prevent the reverse flow of compressed air in the pneumatic system.
One-way valves have direct and rectangular types.Straight-through one way valve is installed on the pipe by threaded connection.Rectangular one-way valve has thread connection, plate connection and flange connection three forms.The liquid control one-way valve is also known as the closed lock valve or the retaining valve, which is the same as the one-way valve to prevent the reverse flow of oil.But when the flow of oil flow in the hydraulic circuit can be used to control the oil pressure, open the one-way valve, so that the oil flow can flow in both directions.The liquid control one-way valve adopts tapered valve core, so the sealing performance is good.The valve can be used as a one-way lock on the oil circuit to protect the oil circuit when it is required to seal the oil circuit.There are two types of leakage and leakage of liquid control one-way valve control oil.Internal leakage can be used to reverse the backpressure of oil flow.Otherwise, it is necessary to use external release to reduce the control of oil pressure.
Characteristics of the one-way valve
A one-way valve is a directional control valve that flows in one direction but not the other.Its working principle is the same as the hydraulic one-way valve.The compressed air enters from the port of P, overcome the spring force and the friction force to open the one-way valve port, and the compressed air flows from P to A;When the P has no compressed air, under the force of spring and A (cavity);The valve port is in A closed state, making it not flow from A to P.Check valve is applied to not allow air flow, such as air compressor to the tank to inflate, between the tank and install a check valve in air compressor, when the compressor stop working, can prevent the compressed air in the tank back into the air compressor.The one-way valve is also used in one-way throttle valve and sequence valve.
Check valves are widely used and there are many types of check valves.
1. Spring type: the liquid is up from the bottom, and the valve valve with the spring control is under the pressure. When the pressure disappears, the spring force will press the disc and close the liquid to reverse flow.Regular check valves for smaller sizes.
2. Gravity type: similar to spring, relying on the self gravity of the disc to prevent backflow.
3. Swing type: the liquid is directly connected in the valve body, with the pressure on the open side of the rotating disc, and when the pressure is lost, the disc relies on the self-resolve-back position, the reverse liquid pressure sealing disc.
4. Plastic diaphragm: shell and diaphragm are plastic. The general shell is ABS,PE,PP,NYLON, PC. Diaphragm has silicone resin, fluorine resin etc.
Other one-way valves (check valves), such as blow-down check valves, safety valves and the use of check valves are of the same principle.
The effect of the reverse check valve is to only allow the medium to flow in one direction, and to prevent the reverse flow.Normally this valve is operated automatically, and under a fluid pressure that flows in one direction, the disc opens;When the fluid is in the opposite direction, the self - overlapping disc of the fluid pressure and the disc ACTS on the seat, thus cutting off the flow.The internal thread check valve, the butterfly check valve is in this type of valve, which includes swing check and lift check valves.The swing check valve has a hinge mechanism, and a gate like valve is free to rest on the inclined seat surface.In order to ensure that each disc to seat the appropriate location, in valve design hinge agencies, so that the disc with enough space of a swing, and real, comprehensive, and the valve seat contact.The disc can be made entirely of metal and can be embedded in the metal with leather, rubber or synthetic coverage depending on the performance requirements.When the swing check valve is fully open, the fluid pressure is almost impervious, so the pressure drop through the valve is relatively small.The valve flap of the lift check valve is located on the seat seal on the valve body.In addition to this check valve can be freely valve movements, like the rest of the cut-off valve, fluid pressure from the valve seat sealing surface lift, medium return led to the disc back to seat, and cut off the flow.Depending on the conditions of use, the disc may be an all-metal structure or in the form of a rubber pad or rubber ring on the disc rack.Like a cut-off valve, fluid through the lift check valve channel is narrow, so the lift check valve through the pressure drop than the swing check valves are bigger, and swing check valves are very few restrictions.