pressure testing used hot water heater?

how do you pressure test a used cast iron hot water radiator prior to installing. The radiator manufacturer is American Radiator. It is an upright radiator made up of 20 segments, total o.a. 10" wide x 20'' high x 54" long and was manufactered in early 1900. Water connections are at each end on the lowest point of the heater and are bled at the top on one end.

roger wood
November 2008