Check valves
A check valve is a type of protection for pipe fittings, the task of which is to prevent the movement of in-pipe substances in the opposite direction.
Depending on its structure and material, the device can be used when working with both aggressive and neutral substrates of pipe systems for various purposes. In this case, check valves have a nominal diameter from 10 to 700 mm. The maximum temperature for which they are designed reaches 300°C, and the maximum nominal pressure is 40 kg/cm².
Working substances are among the most common: water; air; gas; sewage; petroleum products; steam; slightly aggressive environments; wastewater.
According to their design, such hydraulic valves are:
- Lifting. This is a classic design in which the liquid, by the force of its flow, lifts the shutter. If the movement of the lubricant stops, the valve closes and prevents the working fluid from escaping in the opposite direction.
- Flanged. The locking element is a flap that opens under the force of a moving fluid. In the event of a backflow, this flap closes under its own weight.
- Ball ones. The cast iron ball is pushed into the niche when the oil moves directly. If the direction of flow changes abruptly, the ball drops, further pressed by oil.
- Disc-shaped. The diameter of the pipeline in this case is covered by a disk with a spring. When the working fluid acts on the valve, this spring is compressed, and the fluid can move through the pipeline. When the required pressure is lost, the spring turns the disk and closes the pipe along its entire diameter.
- Bivalve. They have two doors that are attached to one axis in the center of the pipe. A sudden change in flow direction causes the springs to press these flaps against the seat.
- Spring springs. An important feature of such structures is that for the mechanism to operate, the liquid flow must gain a certain force, but the lumen of the pipe is blocked even before reverse flow occurs.
In addition to this classification, check valves also differ in the method of installation in the hydraulic system and the material of the body.
