900 DIN Spring loaded Pressure Safety Valve

DIN Standard Safety Valve Features: 

Safety valves were first used on steam boilers during the industrial revolution. Early boilers without them were prone to accidental Explosion.
Safety valves also evolved to protect equipment such as pressure vessel (fired or not) and heat exchangers. Safety valve term should be limited to compressible fluid application (gas, vapor, steam).

The two general types of protection encountered in industry are thermal protection and flow protection.