End-of-line pressure venting valves / vacuum venting valves

They are used as protective equipment with pressure - and vacuum installations.
Following categories exist.
- Venting valves with standard disc (weight - or spring loading pallet), with proportional opening; flow relief across an overpressure percentage range up to 40%.
- Venting valves with full-lift disc; relief across the [set pressure … set pressure + 10%] range, until complete opening. Maximum set value shall be established at 10% under the maximum admitted pressure value.
 
Pressure control makes a highly precise correlation between pallet dimensions (diameter and height) and seat. By choosing a correct dimensioning, the "10% technique" allows for setting the pressure at only 10% under the maximum admitted pressure value. At tanks equipped with emergency valves, the venting valve shall be set under the opening pressure value of the emergency valve. The venting valve opens completely similarly to a usual emergency valve, but at minimal pressure changes.
 
For applications with temperatures much under frosting limit, diaphragm valves are used. The end-of-line venting valves allow for high vapour flow rates under insignificant loss conditions.
 
Venting valves are used to aerate tanks or other plant when vacuum – or pressure value goes beyond a maximum admitted limit. In this respect, the PROTEGO product range offers pressure venting valves, vacuum venting valves and also a combination model of venting valve fit for both pressure and vacuum.
 
The pilot venting valves are used when the application requires a special response characteristic or when the valve shall remain closed until a certain pressure value. The rapid venting valves equip tanks on naval vessels.
 
According to API 2000 edition 6/ ISO 28300 standard, basic dimensioning criteria of end-of-line venting valves are as follows.
- Tank dimensions (diameter and height).
- Tank position and structure (insulated or uninsulated).
- Working fluid pumping flow rates (loading and unloading).
- Geographical latitude of tank location.
- Mean ambient temperature at tank location.