But Thompson said on Wednesday the balloons cost several hundred thousand dollars each, and he estimated the team lost $60,000 to $70,000 in helium with the aborted jump.
How would the hydrogen be stored before used to inflate the ballon?How would the hydrogen be transported to the site?If the ballon ruptures during inflation, what would be the correct course of action to ensure no one was engulfed in flames?Compressed hydrogen gas violently escaping from its container produces enough energy to ignite the hydrogen. In other words, if you drop a wrench and it cracks a pipe or fitting you will be very lucky if your destination is the hospital.
If the balloon ruptures, I think mitigation would be to wait a few seconds, the hydrogen will be 50' off the ground by then and very soon afterwards at the top of the atmosphere.
Quote from: JoeN on Oct 18, 2012, 09:04 pmIf the balloon ruptures, I think mitigation would be to wait a few seconds, the hydrogen will be 50' off the ground by then and very soon afterwards at the top of the atmosphere.Would you bet the lives of dozens of people on that?
Most likely leakage. The Helium Molecule is larger than the Hydrogen molecule so it leaks less. Pump any other gas into a container and it stays there. Pump hydrogen in and if there is ANY thought of a crack it will all leak out.Another possibility is the amount of expansion of hydrogen over helium.And for the volumn it might just be too dangerous...Hyrogen will burn in almost any mixture with oxygen. Some gases can actually self smother because they need a critical mixture to burn.
hydrogen mixed with air does need a spark to set it off.
You can get sparks from static but hey they send instrumented balloons up on hydrogen all the time... I wonder how many of those burn up?
The heat generated from pressurized hydrogen escaping
Joule-Thomson appear to disagree with you...http://en.wikipedia.org/wiki/Joule%E2%80%93Thomson_effectI have first-hand knowledge that escaping hydrogen can ignite in the way I've described.
Helium and hydrogen are two gases whose Joule-Thomson inversion temperatures at a pressure of one atmosphere are very low (e.g., about 51 K (?222 °C) for helium). Thus, helium and hydrogen warm up when expanded at constant enthalpy at typical room temperatures.