A back pressure valve operates through the force of an internal spring: when the system pressure is lower than the set pressure, the diaphragm blocks the pipeline under the spring force; when the system pressure is higher than the set pressure, the diaphragm compresses the spring, opening the pipeline and allowing liquid to flow through the back pressure valve. The structure of a back pressure valve is similar to that of a check valve, but its opening pressure is higher, ranging from 0.2 to 1.6 MPa.
In situations where the pressure in the pipeline or equipment container is unstable, the back pressure valve can maintain the required pressure in the pipeline, allowing the pump to output flow normally. Furthermore, siphoning often occurs at the pump outlet due to gravity or other factors; the back pressure valve can reduce flow and pressure fluctuations caused by siphoning. For positive displacement pumps such as metering pumps, over-pumping can occur when operating at low system pressures. To prevent such problems, the metering pump outlet must have a back pressure of at least 0.7 Bar, typically achieved by installing a back pressure valve at the metering pump outlet.
