The non-return valve is used to give the internal medium the desired direction, and it is the only thing done to exclude the possibility of the existing medium moving in the opposite direction. This type of reinforcement is presented in several forms. The backpressure valve can be rotary and lifting.
For tank farms and water intake devices, a valve with a mesh is used, it is also called a receiving valve. Installation of this type of reinforcement is always carried out in a single direction. An increase in the sensitivity of the valve to a change in the flow of the medium is possible due to the fact that the plate is equipped with a load or spring. However, this can cause a loss of pressure, as well as increased energy consumption, which is required to move the internal environment of the pipeline. In some cases, he is obliged to allow the circulation of the coolant in a natural way. In such devices, complete blocking occurs with a reverse flow, which is higher than the calculated one. However, the circulation in this case does not stop, since there is a small hole in the element disk, which takes responsibility for the necessary circulation of the medium inside the pipeline.
Sometimes a non-return valve is applicable as non-return valves. This possibility is realized due to the fact that the device is equipped with a spindle or other element that allows you to squeeze the plate to the saddle, thereby fixing it. Lift valves are much simpler in design than rotary valves, but at the same time they are absolutely identical in reliability and tightness. The disadvantage of this type of device is that when working in a polluted environment, sometimes the shutter sticks. Lift check valves are used for relatively small bore diameters and clean media. In other cases, it is advisable to use a rotary type.
The ventilation check valve is designed to block the duct section in automatic mode when the fan is turned off. The principle of operation of these devices is gravitational. The valve flaps open under the influence of air flow, and when it stops supplying, they return to their original position also in automatic mode. Such an operating principle serves as a limitation for the use of this type: on the horizontal section it must be installed with a clear “top-bottom” orientation of the device, and on the vertical it is used only if the flow direction is up. For this type of fittings, it is not customary to impose tightness requirements.
In other areas, a non-return valve is also applicable. Sewerage uses it to block the flow in the opposite direction in the event of clogging of pipes with various drains. Different types of devices are designed for different types of pipes, this allows you to achieve the desired effect in each specific situation.
Check valves are made from different materials. A specific type is selected based on the type of pipe it fits into.