Pressure Relief Valves (safety valves or bypass valves)
Pressure relief valves protect expensive capital equipment such as the pump, system, or tank from an upset condition (pressure spikes, over pressurization, a closed valve, etc.). They are a normally closed valve that operates (opens) when the pressure exceeds the pre-set value. They allow the excess pressure to be bypassed and safely discharged back into the supply tank or inlet piping. They maximize the uptime and ensure proper function for all ancillary devices connected.
Back Pressure Valves (loading valves / Anti-syphon Valves)
Backpressure ensures that dosing pump outputs have consistent flows. They do this by applying a minimum constant pressure that a pump must push against to maintain reliable check valve seating (closing). Consistent closure of its suction and discharge check valves on reciprocating pumps (like a diaphragm or plunger pump) allow for higher accuracy and stable operation.
An anti-siphon valve is also a very important function, ensuring that a Venturi is not created which could override the metering pump. This function cannot be achieved with a check valve.