Model No: 193

Storagetech™’s Model 193 Vacuum Relief Valve ensures that the pressure in the bulk storage tank does not fall below the safe operating range needed to prevent implosion damage. It is fitted on a tank roof flange or pipe that connects to the vapour space of a storage tank.

In the closed position the spring-loaded pallet and diaphragm assembly is held tightly against a seal to prevent the loss of vapour to atmosphere. As the internal pressure in the tank reduces, due to emptying, the balance between the tank pressure and the external atmospheric pressure changes, and when the set pressure of the unit is reached, the diaphragm will open to admit air and rebalance the internal pressure. The opening set-point is selectable from a range between +61 mbar and +1000 mbar (+24 inch W.C. and 400 inch W.C.)

The vent will close when the tank returns to a positive pressure. A mesh filter screen over the air inlet port prevents the ingress of atmosphere-borne debris.

The integrity of the seal is tested for leakage in accordance with API Standard 2521 – Use of Pressure-Vacuum Vent Valves for Atmospheric Loss.

The size of the vent should be calculated in accordance with API Standard 2000 (ISO 28300) – Venting Atmospheric and Low-Pressure Storage Tanks or other international standards.