---------------------------------------------------------- Cessna-List Digest Archive --- Total Messages Posted Sat 07/19/03: 1 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 07:10 AM - butane/propane fuel cylinders (Gary Casey) ________________________________ Message 1 _____________________________________ Time: 07:10:34 AM PST US From: "Gary Casey" Subject: Cessna-List: butane/propane fuel cylinders --> Cessna-List message posted by: "Gary Casey" <> The difference in atomospheric pressure going from sea level to 10,000 feet is only about 5psi. Butane exists at fairly low pressure and propane is at maybe 100 psi at about 100 degrees F. In either case the tanks are certainly designed with far higher burst pressure margin than 5 psi. In fact, the pressure in the tanks will vary dramatically with temperature and going to altitude will expose the tank to much lower pressures than leaving it out in the sun, which it is designed to tolerate. I wouldn't worry about it at all, but I would use normal precautions in carrying fuel in the passenger compartment. The comment about scuba tanks is puzzling as they typically are pressurized to a few thousand psi and the tanks are certified to several times that. An extra 5 psi out of 5,000 is only 0.1% extra pressure. That same change in pressure can be obtained by increasing the temperature of the tank only 0.5 degrees F! I wouldn't even think about taking the air out of a scuba tank except if you were worried about breaking off the valve in a crash or when flailing about in turbulence, creating missile. If the relief valve popped (no more likely than when strapped to your back) it would make a lot of noise. I think airlines like them empty just because (the same reason they don't like you using your GPS in flight). Gary Casey