Swing check valves are widely used in petrochemical, pharmaceutical and power pipeline transportation.In these systems often need to transport some oil, steam, nitric acid, strong oxidizing medium. Swing check valve is through the internal rocker swing type structure to avoid these media will not backflow phenomenon, and avoid internal media outflow.
Swing check valves, like lift check valves, are used in transportation control of piping systems.However, lift check valves can only be used in horizontal piping, whereas swing check valves can be installed in both horizontal and vertical piping.But the swing check valve and the lifting check valve work principle is the same, is through the medium flow pressure action and the pressure action of the disc itself and action, usually internal medium flow inlet direction can impact to the disc rotation to the other side.
Swing check valve is mainly composed of valve body, cover, disc and rocker four parts, in addition, there are auxiliary spring and hammer structure to improve the sealing of pipeline, this is because in the low pressure situation, swing check valve sealing is not enough.
Metal seats of swing check valves are often worn and the internal pressure in the pipe of swing check valves can exceed the relief of disc return valves.Therefore, the damped structure is set on the valve valve in the check valve to avoid that when the medium flows in the pipeline, the lifting of the check valve should be overcome to cause the disc to close suddenly, causing water hammer in the pipeline and wear on the valve seat.
Swing check valves control the swing flow in the pipe through the internal disc and rocker shaft.The passageway in the valve is streamlined, thus creating greater flow resistance.Swing check valves open because of the gravity of the disc, creating resistance to the moving medium.
When the swing check valve is installed in the vertical pipe, the internal medium in the pipe flows from the bottom to the top. If there is an emergency stop, the internal valve will flow back into the pipe together with the internal medium due to its own gravity. At the same time, the internal valve will automatically close to play a command role.When swing check valves are installed in horizontal piping, the internal media flow through the pipe in a single direction can also be automatically closed.
In short, swing check valve as an automatic device, all the internal opening and closing devices are acting on the inside of the valve, will not penetrate the valve body, so as to avoid the possibility of liquid leakage in the pipeline, through the spherical joint structure so that the disc can maintain a certain degree of freedom, can obtain a longer service life.