Safety Valves and Fittings

Here you will find answers to questions about safety valves and fittings that we are asked particularly frequently.

In case you have a special questions please contact us. We will be pleased to help you and give you our advice.


What is a safety valve?

Definition of a safety valve according to DIN EN ISO 4126-1
A safety valve prevents a predefined pressure from being exceeded. When the pressure is exceeded, the valve opens and the excess pressure is released and the medium is discharged. The safety valve is activated without auxiliary energy and is triggered purely by the medium. As soon as normal working pressure conditions have been restored, the safety valve closes and further outflow of the medium is prevented.

A safety valve is used to protect a system as a last safety instance. In the case of systems requiring approval or systems that fall under the European Pressure Equipment Directive, for example, corresponding tests and approvals are required for the valves.

How is a safety valve constructed?

Even though each series differs in the field of safety valves, the main components of each valve are similar. The optimal design of the component geometry is ensured by flow simulations and elaborate function tests.

What's the difference between a safety valve and a pressure relief valve

Safety valves

  • Certified valves with TÜV / PED and/or CE Type Test Approval
  • Normal lift- Full lift opening / closing characteristic
  • Higher blow-off capacities than pressure relief valves

Pressure relief valves

  • Valve without certification/approval (without safety function according to PED)
  • Proportional opening- / closing characteristic
  • Lower blow-off capacities than safety valves

When do you use a pressure relief valve or a safety valve?

Whether a plant operator is allowed to use a pressure relief valve, or if he must usa a certified safety valve depends primarily on the type of application or plant. Both valve types are intended to be the last safety device in a system. In the case of systems or plants requiring official approval or which fall under the European Pressure Equipment Directive (PED), the valve must hold corresponding approvals and certifications.

How does a safety valve work?

The function of a safety valve can be traced back to a simple balance of forces between the pressure spring force and the medium force.

When at rest and installed on the system in normal operation, the force of the pressure spring is greater than the medium force, whereby the valve is closed and seals to the outside.

If the set pressure of the valve is exceeded due to increased system pressure, the valve opens and allows the pressure to be relieved by the medium escaping. After the pressure in the system has been reduced below the closing pressure, the valve closes tightly again.


How can I calculate safety valves?

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