Stainless Steel Air Operated Vapour Vents


Liquip's AVV3SST air operated chemical vapour vent has been designed for superior chemical compatibility and resistance.

The AVV3SST is a sequential vapour vent with the exhaust of the previous valve opening the next in line. The exhaust from the last vent can be used via a pressure switch to activate the overfill protection system once all vents are open.

It has a 90mm nominal diameter outlet for reduced pressure drop and increased vapour flow during loading and unloading.


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  • Adjustment free.
  • Low maintenance.
  • 90mm nominal diameter outlet for a minimum full 80mm flow throughout.
  • Piston operation for sequential operation.
  • Downward opening poppet to prevent leaks from product surge, in the event of a tanker rollover.
  • The sequencing valve is offered to ensure the main poppet is fully open before next vent opens.
  • The end signal can then be used to allow loading/unloading in the certainty that all vapour vent poppets are open.
  • Air cylinder is serviceable without removing the valve from tank.

Operating Pressure
Operating air cylinder pressure: 70 to 900 kPa (normal 500 kPa).

Vacuum opening pressure: -7 kPa vacuum.

Air Consumption
1 litre free air per stroke.

Bolted from the outside to a blind Stainless Steel weld flange.

Flange mount - 8 holes equally spaced, 11mm on a 130mm PCD. 154mm OD.

-316 Stainless Steel body.
-316 Stainless Steel trim with FFKM, Viton and Teflon encapsulated seals.

AVV3SST: Chemical Vapour Vent.

AVV3SS-10: Stainless Steel weld in mount flange to mount on tank top.

AVV3SS-11: 316 Stainless Steel Spark Arresting Gauze (optional).

AVV3-12: Polyurethane louvre kit with spare arresting gauze.

VH3.5: 90mm nitrile hose (check suitability for chemical products).