Walchem Back Pressure / Anti-Siphon valves provide stability and safety to your metering pump installations. All metering pump require back pressure to operate correctly and often installations do not provide enough back pressure to stabilize the pump flow – and some have even pressures lower than atmospheric, creating a siphoning situation. Back pressure / anti-siphon valves can provide the required back pressure to the pumps when it is not created by the application. They also will assist in stopping a siphon condition. Additionally, when they are used in a bypass, they act as a pressure relief valve, providing for over-pressurization protection to the pump and discharge piping assembly, critical for mechanically actuated metering pumps.