A basic economy brass (up to 1¼") or bronze (1½" and 2") spring safety pressure relief valve used with a pressurized water system to prevent pumps from 'dead-heading' when the pressure reaches a pre-set limit due to closed valves. When the system set pressure is exceeded, the valve opens allowing the water to bypass and therefore reduce the pressure. Generally installed to vent either into a water tank or to waste, this will allow the water to circulate without causing damage to the pump.

Maximum pressure is 10 bar and available with an adjustable spring range of 2 - 9 bar only.