Pressure relief valve

Illustrated explanation

Choose a pressure reference and a protective device

2Pressure relief valve
Choose a pressure reference and a protective deviceCallout 1: Absolute / gauge. Callout 2: Relief valve. Absolute pressure is referenced to vacuum, while gauge pressure is referenced to the local atmosphere. A relief valve has a separate opening and flow function. Current term: Pressure relief valve, callout 2. 1VacuumAtmosphereSystemAbsolute / gauge 2Relief valve
  1. Absolute / gauge pressure

    The longer span is referenced to vacuum; the shorter span is referenced to local atmosphere. State the reference whenever reporting pressure.

  2. Pressure relief valveThis term

    The valve opens under its specified pressure relationship. Select its set point, capacity and failure response independently of a normal breather.

Absolute pressure is referenced to vacuum, while gauge pressure is referenced to the local atmosphere. A relief valve has a separate opening and flow function.

Conceptual reference axis and valve section. Vent equalization and pressure relief are not interchangeable, and no set pressure or capacity is assigned.

ReferencesISO 80000-4:2019 — Quantities and units — MechanicsISO 20484:2017 — Leak testing — VocabularyISO 4126-1:2013 — Safety devices against excess pressure — Safety valves