Hydrogen is the lightest of all naturally occurring gases. It is colorless, odorless, and extremely flammable. Its unique properties, such as flammable over a wide range of concentrations (4%-75% in air) and low ignition energy, are what contribute to its extreme flammable nature. The flame of hydrogen is nearly invisible and has a high temperature which reaches 3,713 °F, as compared to gasoline which has a flame that reaches a temperature of 2,276°F. It is also important to note that hydrogen flames radiate little infrared heat, but substantial ultraviolet radiation, which means that when you are near a hydrogen flame, there is little sensation of heat. Two major physical hazards of hydrogen are its ability to have a fire at only 4% concentration and an explosion at 18% concentration in air.
Many labs on campus have compressed gas cylinders of hydrogen and it’s essential to have the knowledge to use, move, and store the tanks safely. When beginning to use a new tank of hydrogen, only the regulator designed for hydrogen is to be used. Never use tools to open the valves due to the risk of a spark. Open the valve slowly to allow the gas to flow with as little friction as possible. Valves should be closed when the cylinder is not in use. When moving a compressed gas cylinder the valve cover must be in place and only the proper transporting device is to be used, such as a cylinder cart. The cylinders are to be stored in an upright position and strapped or bolted to walls to eliminate the hazard of being knocked over and becoming propelling rockets due to their pressurized nature. They must be separated from oxidizing gases by a distance of 20 feet or by a 5 foot high fire barrier that has a half hour fire rating. Tanks that are not currently being used should be stored in another location away from the active tank.
To help in the detection of leaks, hydrogen detection alarms should be installed on the ceiling above the tanks to alert lab personnel the concentration in the lab has reached 1%. This is critical because the hydrogen molecules are so small they are able to escape through finite spaces that other gases cannot. If the alarm does go off and there is not an immediate fire, turn the hydrogen source off, evacuate the lab, and call 911 from the nearest campus phone outside of the laboratory or 274-7911 from a cell phone and inform the emergency dispatch operator of the alarm. If a fire has started turn the hydrogen source off (if it is possible to shut off safely), pull the fire alarm, and call 911 from another building or 274-7911 from a cell phone and inform the emergency dispatch operator of the fire.
If you are a research lab on campus that uses hydrogen gas, please know and understand all the procedures and hazards associated with it. Have an emergency plan in place that all lab personnel are familiar with and at the end of the day everyone goes home the way they came in. Give hydrogen gas the respect it deserves.