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  • How to completely refill a 1lb "disposable" propane Bottle

    I've read a few of your comments and I'd say nice job sticking with the facts on the saturated liquid-vapor lines of reasoning. I don't quite understand the data presented in your post here. You might be underestimating the amount by which liquid propane expands with temperature. We get accustom to water, for example, but without the hydrogen bonding to hold it back, liquid propane expands considerably more easily than our experiences with water. From one source, the coefficient of thermal expansion for liquid propane is about 0.00155 / C. So, if a tank is filled on the coldest of days (-20C) here in the midwest, then on the hottest of days (40C) the liquid propane will have expanded by about 9%. If the original liquid volume was about 90% of the tank volume, it would now be about...see more »I've read a few of your comments and I'd say nice job sticking with the facts on the saturated liquid-vapor lines of reasoning. I don't quite understand the data presented in your post here. You might be underestimating the amount by which liquid propane expands with temperature. We get accustom to water, for example, but without the hydrogen bonding to hold it back, liquid propane expands considerably more easily than our experiences with water. From one source, the coefficient of thermal expansion for liquid propane is about 0.00155 / C. So, if a tank is filled on the coldest of days (-20C) here in the midwest, then on the hottest of days (40C) the liquid propane will have expanded by about 9%. If the original liquid volume was about 90% of the tank volume, it would now be about 98%. Of course, things could get worse in the trunk of a car on that hot day. To leave a "public safety" size margin for error, it seems the industry aims for 80% fill level. I think this is what dmmartindale was pointing out as well. High liquid levels may also make it more likely that if some over-pressure condition forces the relief valve open, that liquid propane (now at a boil due to the dropping pressure) might get forced through the relief valve - releasing a truly unexpected volume of propane vapor that might reach a more distant ignition source or displace O2 in some confined space .I also came across information that the pressure relief valve typically is calibrated to open at an internal pressure of about 375 psi. For saturated liquid-vapor in the tank, this pressure would occur at about 75C (165F). So much for carelessly transporting propane tanks in a closed car.here is the source for the coefficient (thanks google): http://abiquim.org.br/congresso/cong_cd/fullpapers...

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