Emergency Pressure Vent Cover Model EFSWE30A is weight loaded release to ATM, made of materials Aluminum, Carbon Steel, Stainless Steel. Model EFSWE30 is designed to protect the tank against rupture or explosion that could result from excessive internal pressures caused by fire etc. Model EFSWE30 is designed to provide emergency relief capacity beyond that furnished by the normal operating pressure relief valve on the storage tank. The feature of Model EFSWE30 is that the pressure relief cover is designed to lift only far enough to flow its rated capacity should high tank pressure be encountered then reseal automatically when the tank pressure is reduced.
API Standard 2000 for Venting / Atmospheric and Low Pressure storage Tanks / SIZING A PRESSURE/VACUUM RELIEF VALVE
API standards are provided as an engineering aid for specification and selection of “normal” and “emergency” pressure and vacuum relief valves for aboveground liquid petroleum storage tanks. Normal venting capacity is obtained without exceeding pressure or vacuum that would cause physical damage or permanent deformation to the tank. The following will help in sizing a pressure/vacuum valve:
1. NORMAL RELIEF : the sum of vapor replacement resulting from emptying or filling and thermal in-breathing or out-breathing.
2. EMERGENCY RELIEF : thermal out-breathing from fire exposure.
3. ALL TANKS : generally require the sizing of a normal pressure and vacuum relief valve to be sized and an independent emergency relief valve to be sized separately.
4. FLOW CURVES : these curves provide pressure and vacuum capacity which is required for sizing.