Vent valves for tanks
Inside large terminal tanks, the pressure rises and lowers constantly as a result of change in the ambient air temperature. The same happens when the tanks are being loaded or discharged. These pressure deviations are levelled with the help of so-called vent valves or pressure and vacuum relief valves. The set pressures of these valves are typically in the range of only some tens of mbar.
PROTEGO vent valves can be installed onto the tank, in which case the vent valve exhausts to ambient air and the compensating air is also taken in from outside the tank. Vent valves can also be installed in the line, in which case the exhaust gases are directed into a collection tank, for example.
It is possible to supply the valves complete with a steam supply so that, for example, exhaust gases from sulphur or bitumen tanks will not deposit on the valve disc, but can be blown out as gas.
Advantages of the high-lift disc structure
The competitive advantage of the PROTEGO model range is the high-lift disc structure owing to which the valve can be set to open by only 10% before it needs to be fully open. In so-called conventional models, the valve starts to open as much as 25% before being fully open. By the time a conventional valve already starts blowing gases into outdoor air, the PROTEGO valve remains closed due to its high-lift structure. For example, when using nitriding, it is important that no expensive nitrogen gas is released needlessly into the outdoor air.
Vent valves can be separate pressure and vacuum relief valves or their combinations of them.
Vent valves can also be equipped with an integrated flame damper.
During an internal training session at the Protego test facility in Braunschweig, Germany, we carried out a test in which a pressure safety valve released a flammable gas mixture into the outside air and a spark ignited the gas mixture.
See what followed.