The check valves are the one-way valves with the simplest mechanism, they are designed to allow the fluid in one direction and block it in the opposite, that’s all. However, the check valve has many uses either in a circuit or as an upgrade to an existing machine.
The check valves are manufactured in cast iron or forging and in different materials: Bronze (especially to work with seawater), carbon steel, stainless steel (petrochemical sector), iron, forged steel, PVC or brass.
The most common use for a check valve is to prevent backward fluid transmission s, and it is the pressure that closes the circuit anyway, in this way preserves pressure while feeding is unloaded. For example, after a pump in a system that uses an accumulator, preventing the energy from returning to the pump and avoiding a deburring. It is also required in more complex load sensing applications or in alternative automated lines.
In addition, it can be a definitive solution to the dreaded water hammer and thermosyphons if it is installed in the right section of pipe.
There are up to 4 different types of check valve:
- Oscillating flap check valve: This valve contains a flap inside that acts as a shutter through the force of gravity when the fluid moves in the opposite direction to the desired one.
- Disc check valve: Valve that closes by means of a spring at a certain pressure.
- Piston check valve: This check valve design closes thanks to a cylindrical piston located inside that rises or falls depending on the direction of the flow.
- Ball check valve: It is a design specialized in the transportation of dirty, corrosive and / or particulate fluids in suspension, so a ball (usually PVC) is used to prevent dirt from sticking to the dial.