A safety valve is a fitting, which, by automatically opening, prevents the system from surpassing a predefined overpressure and is intended to automatically close again after a drop in pressure. The requirements placed on a safety valve are described in the Pressure Equipment Directive. A pressure-limiting valve is frequently used as a safety valve. After it is triggered (start of opening), the safety valve must deliver the stroke required for the mass flow to be discharged within a pressure increase of no greater than 10% of the pressure setting. As a rule, safety valves are subject to component testing. Each safety valve must be secured against unauthorised changes to the pressure setting and the functional principle. Common applications: In hydraulic systems in differential cylinders (press cylinders) on the piston rod side to protect against pressure boosting, and to protect hydraulic accumulators.
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