· Pressure relief valves are used on liquid storage tanks and other process vessels or systems to prevent structural damage due to excess internal pressure.
· Storage tanks are pressurized when liquid is pumped in, compressing the existing vapor or when rising temperatures cause increase devaporation or expansion of existing vapor.
· To prevent tank damage, vapor must be allowed into or out of the tank at specified pressure condition.The volume rate of venting depends upon the tank size, volatility of the tank contents, the pumping rates and the temperature.
