CGA P-40

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Cryogenic storage tanks are normally refilled from transports that use high flow centrifugal pumping systems. These pumping systems are capable of pressures that exceed the tank's maximum allowable working pressure and flow rates that may exceed the capacity of the tank's pressure relief system.

This publication provides the complete equation set for determining the flow capacity of the tank's pressure relief and filling systems based upon specific line sizes, valves, and other components. Formulas for sizing a flow-limiting orifice when required to restrict the fill rate to match the relief system are included. The publication includes a discussion of alternative solutions such as an external protection device as well as sample calculations.

It is the responsibility of each tank owner to ensure that pressure relief devices are properly sized for the tank refill operation.