General Requirements This standard covers the normal and emergency venting requirements for aboveground liquid petroleum or petroleum products storage tanks and aboveground and underground refrigerated storage tanks designed for operation at pressures from vacuum through 15 pounds per square inch gauge (1.034 bar gauge). Discussed in this standard are the causes of overpressure or vacuum; determination of venting requirements; means of venting; selection@ installation@ and maintenance of vents; and testing and marking of relief devices. The venting requirements provided in this standard are based on studies using liquid hexane. Sound engineering judgment should be applied when extrapolating these results to other liquids. Detailed engineering studies of a particular tank and its operating conditions may indicate that the appropriate venting capacity for the tank is not the venting capacity estimated in accordance with this standard. If a tank's operating conditions could deviate from those used in developing this standard@ detailed engineering studies should be performed.