The various types of valves and relief valves

Valves and relief valves form two broad categories of equipment grouped under the generic term of industrial valves and fittings.



  • Valves are mechanical devices used to modify the flow of a liquid or gas in a closed or open circuit.
  • There are two broad families of valves: control valves and shut-off valves.
  • Valves can be equipped with an actuator (electric, pneumatic or hydraulic) or operated manually.
  • Valves are mainly of the plug, pressure-retaining, wedge-gate, spherical, gate and butterfly types.


Relief valves

  • Relief valves are mechanical devices placed on pipes or pressure containers.
  • The valves lower the internal pressure of this equipment according to a predefined value (calibration). They are essential for protecting the safety of people and equipment.
  • There are two main families of relief valves: direct action (a single flap) or indirect action (main and auxiliary flaps).
  • The various types of relief valves are relief, pressure-relief, sequence, pressure-reducing, back-pressure, etc.