Warming of liquid hydrogen contained in an enclosed vessel to above its critical temperature can cause bursting of that container. In particular, hydrogen cylinders should be clamped or otherwise supported in place and used only in areas free of ignition sources and separate from oxidizers. Expansion of hydrogen released rapidly from a compressed cylinder will cause evolution of heat due to its negative Joule-Thompson coefficient. If large amounts of hydrogen are inhaled, move the person to fresh air and seek medical attention at once. In the event of a leak, remove all ignition sources and allow the hydrogen to disperse with increased ventilation.
Hydrogen disperses rapidly in normal open environments.
Respiratory protection may be necessary in the event of a release in a confined area. Disposal Excess hydrogen cylinders should be returned to the vendor. Excess hydrogen gas present over reaction mixtures should be carefully vented to the atmosphere under conditions of good ventilation after all ignition sources have been removed. For more information on disposal procedures, see Chapter 7 of this volume. The information in this LCSS has been compiled by a committee of the National Research Council from literature sources and Material Safety Data Sheets and is believed to be accurate as of July 1994.