Economic & convenient propane

[jumpin]

But in a "C" sized cylender, the result is about 1000-1300 psi, a full "C" is in the neighborhood of 2200-2600psi depending on temp.

I'm not sure that is correct... the over pressure relief valves are usually set to about 375 psi or 2585 kPa! Are you thinking kPa? 130 psi = 896 kPa