Check valve

Check valves are mechanical devices used in pipeline systems to prevent back-flow. A check valve allows fluid flow only in one direction that’s why it is called a one-way valve or non-return valve. Check Valve works on the principle of differential pressure. It means the check valve will only open if the upstream pressure is more than the downstream pressure. In situations, if downstream pressure is more, the valve will close preventing back-flow. Closure can also be accomplished by the weight of the check mechanism, by a spring, or by a combination of all these means. One of the main applications of check valves is at the pump outlet to protect the equipment from flow reversal.

Check valves are automatic valves and unlike other valves, human intervention or external control is not required for their opening or closing.

As already stated, a check valve operates on the principle of differential pressure. For a check valve to open, it must attain a minimum upstream pressure known as cracking pressure. Depending on the check valve design and size, the cracking pressure changes.