Check Valves in Vietnam

Check Valve (Van một chiều) a valve that closes by fluid pressure to prevent return flow

(Mechanical engineering: Fluid engineering)
A check valve is a valve that is closed by the pressure of a fluid so that the fluid does not flow back in the direction it came from.
Check valves to ensure that fuel flows in only one direction, thus avoiding contamination.
The special coupling device contains a check valve that allows fluid to pass downward but not upward through the casing.
A check valve is a valve that is closed by the pressure of a fluid so that the fluid does not flow back in the direction it came from.

A check valve, one-way valve, reflux valve, retention valve, foot valve, or no-return valve is a valve that regularly allows fluid (liquid or gas) to flow through it in only one direction.

Check valves are two-port valves, one for fluid to enter and another to leave. There are different types of check valves used in a wide variety of applications. Check valves are often part of common household items. Although they are available in a wide range of sizes and costs, check valves generally are very small, simple, and inexpensive.

Check valves operate automatically and most are not controlled by a person or any external control; accordingly, most do not have any valve handle or stem. The bodies (external shells) of most check valves are made of plastic or metal.

An important concept in check valves is the cracking pressure which is the minimum differential upstream pressure between the inlet and outlet at which the valve will operate. Typically, the check valve is designed for and can therefore be specified for a specific cracking pressure.