Angular shaped spring-loaded safety valves made of red brass with stainless steel spring. Set pressure is protected by seal cap. Valve cone can be lifted using lever. Suitable to protect thermostatically protected closed-circuit water heating systems with flow temperatures up to 120 deg. C. For all static heights or nominal powers of more than 350 kW as well as for protection of solar plants up to 120 deg. C, and also to protect indirectly heated heat generators in accordance with DIN 4751 part 2 the safety valves only have to be rated for the flow rate of the expansion water.