Pressure in a propane tank is pretty high...not sure what. Enough to keep the propane in liquid form. Gas is taken off the top of the tank so no luquid should get out. The liquid is actually boiling off in the tank. There is a pressure regulator in the line, at the tank output, that controls the pressure of the gas to the heater. These are sometimes adjustable and this is what he was tweaking. Glad it was a simple solution....or at least hope it is.
Al