PVRV Emergency Relief Valve


Direct acting pressure / vacuum relief valves (also known as breather valves) are low pressure devices specifically designed to protect tanks, process systems and equipment from excessive pressure and vacuum.

PVRVs provide the primary layer of protection for tanks and process systems and minimize emission losses of gases or vapors, thus protecting the people and environment.

Our pressure / vacuum relief valves range includes pressure only, vacuum only and combined pressure/vacuum valves, all available with flanged outlets or vented to atmosphere

Pressure / vacuum relief valves are used extensively on bulk storage tanks, including fixed roof tanks with floating covers, to minimize evaporation loss. The valves prevent the buildup of excessive pressure or vacuum which can unbalance the system or damage the storage vessel.

Pressure and vacuum protection levels are controlled with weighted pallets or springs and can be combined to provide the required pressure/vacuum settings. It is common to combine pallet and spring systems in one unit i.e. pressure settings require a spring section, whilst the vacuum settings use the pallet method.

These are some of the options available for our Breather Valves.

  • Available in Aluminum, Cast Iron, Carbon Steel, Stainless steel & other metals upon request
  • Valve sizes from 25mm (1″) to 300mm (12″)
  • Valve sizing available on your request
  • Full Range of Breather Valve Spares available
  • Breather Valve Servicing and resetting available upon request

The Pressure / Vacuum Relief valves are available in following combinations:

  • The Pressure / Vacuum Relief valves are available in following combinations:
  • Pressure Only Relief Valves
  • Vacuum Only Relief Valves
  • Spring Loaded Relief valves


  1. Digesters
  2. Storage Tank
  3. Fixed roof tank with floating covers
  4. Gas Holders
  5. Chemical processing

Emergency Relief Vents For Tanks

Emergency Relief Vents provide an emergency pressure relief opening for storage tanks when exposed to overpressures

The ERV protects the tank against rupture or explosion which can result from excessive internal pressures caused by an external fire.

They are used extensively on bulk Liquid storage tanks, including floating roof tanks.

Sizes Range from 10″ (250mm) to 36″ (900mm)

Principle of Operation

Emergency relief vents are fitted to storage tanks to allow emergency flow due to the excessive venting requirement from a fire burning around a storage tank. Their use eliminates a costly tank rupture by providing emergency venting from abnormal internal pressure beyond the capability of the pressure relief vent. In the event of a fire the pallet lifts at a pre-determined pressure, thus supplying a large venting area.
These models employ a PTFE insert, affording a tight seal below set pressure, between the pallet and the corrosion resistant seat. The pressure/vacuum model is fitted with an additional spring-loaded vacuum valve that will open under negative pressure to protect the tank from any vacuum condition damage that may occur.

Easy to operate and low maintenance cost

  • Hinged Pallet can be manually lifted allowing access to the tank for cleaning and inspection
  • Manufactured to clients flange requirements
  • Range of sizes and material to suit different applications
  • Wide range of pressure setting to provide maximum tank protection and minimum gas losses
  • Easy to operate and low maintenance cost