Safety Relief Valves - Catalogue / Operating Instructions

WITT is a manufacturer of safety relief valves or pressure relief valves. Safety relief valves respectively pressure relief valves or pressure safety valves are designed to protect against overpressure by discharging pressurised gases and vapours from pipelines, pressure vessels and plant components. Safety relief valves are often the last line of defence against explosion – and such an explosion could be fatal. Other common names for safety relief valves are pressure relief valve, safety valve, or blow-off valve.

What are the benefits of WITT safety relief valves / pressure relief valves?

WITT safety valves are very precise. They are individually preset to open at a predetermined pressure within the range 5 mbar to 45 bar. Their small size and orientation-independent installation allow a wide range of connection options. WITT safety valves also stand out due to their high blow-off flow rates of up to 970m³/h. They can be used within a temperature range of -60° C to +270°C.

TÜV-tested safety valves

For maximum safety, WITT undertakes 100 % testing of each safety relief valve before it is delivered. In addition, WITT offers individual testing of each safety valve by the TÜV, with their certificate as proof of the correct set pressure.

How do safety relief valves / pressure relief valves work?

WITT safety relief valves are direct-acting, spring-loaded valves. When the preset opening pressure is reached, a spring-loaded element in the valve gives way and opens, and the pressure is relieved. One the pressures are equalised, the valve closes automatically and can be reactivated any time the pressure rises again. Depending on the application and the nature of the gas, the safety relief valves can either discharge to atmosphere, or via a connected blow-off line. The opening pressure of the safety valves is preset by WITT at the factory according to the customer’s requirements.

Applications for safety relief valves

Safety relief valves are used in numerous industries and industrial applications where, for example, gases pass through pipelines or where special process vessels have to be filled with gas at a certain pressure.

These include, among other things:

• Pipeline, plant and container construction

• Industrial furnace construction

• Insulators and reactors (e.g. “glovebox” systems)

• hydrogen-powered vehicles
• Additive manufacturing (3D printer)

What materials are safety relief valves made of?

For most industrial applications using technical gases, brass is usually the standard material of construction of the safety relief valve body/housing. For the use of safety relief valves with aggressive and corrosive gases, the housings are made of high-quality stainless steel (1.4541/AISI 321, 1.4404/AISI 316L, 1.4305/AISI 303 or 1.4571/AISI 316Ti). The use of aluminium as a housing material is also possible.

Depending on the type of gas used and individual customer requirements, various sealing materials and elastomers are available to ensure the safety of your systems under even the most difficult conditions.

What connections do pressure relief valves have?

WITT safety relief valves are available with different connections. In addition to the standard versions with the usual internal or external threads, special versions with KF or CF flanges, VCR or UNF threads can also be ordered. Special adapters for connecting the safety valve to a blow-off line are also available.