the diaphragm moves up and the chemical flows out of the relief port back to the chemical tank or the suction side of the pump

please see Bradley 356-35

EF HT 8210B056 AC

2 In Corner Compartments

PANEL-LH PUSH (L)

Apollo Bronze Safety Relief Valve, FNPT Inlet Type, FNPT Outlet Type - 1060505 Capacity-34 oz the diaphragm moves up andASME Section IV Safety Relief Valves, Pressure range: 15 to 160 psig Max. temp.: 250F,Protect against excessive water pressure due to failure of controls to regulate BTU input. High BTU capacity rating. Corrosion resistant with silicone seat. Fabric reinforced, molded diaphragm isolates spring from water at all times. FNPT connections. Designed for boilers, heating systems, and unfired pressure vessels.,Meet ASME Section IV Coded for hot water; HV