Brass safety valves operated by an internal spring. The relief pressure may be adjusted by rotating the external nut. If the set pressure is exceeded the valve vents to atmosphere.
https://www.bes.co.uk/1-2in-bsp-pm-spring-safety-valve-7512/34625Spring Safety Valve - 1/2" BSP PMhttps://www.bes.co.uk/media/catalog/product/1/-/1-2in-bsp-pm-spring-safety-valve_min_7512_P_1.jpg2.462.46GBPInStock/Heating & Ventilation/Central Heating/Valve/Pressure Relief/Stay Safe this Winter77812181212459762Brass safety valves operated by an internal spring. The relief pressure may be adjusted by rotating the external nut. If the set pressure is exceeded the valve vents to atmosphere.Unbranded00https://www.bes.co.uk/media/catalog/product/1/-/1-2in-bsp-pm-spring-safety-valve_min_7512_L_1.jpgadd-to-cartfacet_type:Spring Safety Valvespecial_price:2.460000more_sizes:7513products_related:6921,6920,6918,11346,11347,11348,18862,20010,15583,23390,23364,23475sku:7512Spring Safety Valve75136921,6920,6918,11346,11347,11348,18862,20010,15583,23390,23364,2347575122.460000No{"Connection":"BSP PM","Size":"1\/2"","Type":"Spring Safety Valve"}Unbranded1/2"