The Challenge
A heavy-guage pressure tank was designed and built so that the pressure would drop no more than 4 psi in one hour. The tank was equipped with a pressure gauge mounted on the top. The valve to be tested was installed at bottom of tank. To heat the vessel uniformly, accurately and constantly during the test, temperate was maintained at 500° F. 

The Solution
Three pairs of Chromalox SE-2450 electric Strip Heaters were clamped 120° apart around the tank circumference to welded-on studs. Heaters were clamped tight to deliver heat uniformly over the entire length of the tank. The control used was a thermoswitch mounted through the side of the tank opposite the valve. Aluminum foil insulation surrounds tank to retain heat and increase the efficiency.

Benefits
It was a simple, convenient and inexpensive method to achieve the desired controlled results.  This solution permitted an integrated installation not subject to possible interruptions during tests, and allowed a portable setup which could be easily removed from the laboratory when not in use.