Hydrogen safety

Hydrogen safety covers the safe production, handling and use of <a href="/facts/Hydrogen/BoYHjl0J">hydrogen</a>, particularly <a href="/facts/Hydrogen_gas/BoYHjl0J">hydrogen gas</a> fuel and <a href="/facts/Liquid_hydrogen/Vpk3Gb8P">liquid hydrogen</a>. Hydrogen possesses the <a href="/facts/NFPA_704/7IgHH9Dv">NFPA 704</a>'s highest rating of four on the <a href="/facts/Flammability/1QexTQ4T">flammability</a> scale because it is flammable when mixed even in small amounts with ordinary air. Ignition can occur at a volumetric ratio of hydrogen to air as low as 4% due to the oxygen in the air and the simplicity and chemical properties of the reaction. However, hydrogen has no rating for innate hazard for <a href="/facts/Reactivity_(chemistry)/PuJ2pmRT">reactivity</a> or <a href="/facts/Toxicity/qa96rs60">toxicity</a>. The storage and use of hydrogen poses unique challenges due to its ease of leaking as a <a href="/facts/Gaseous/hVVAoodV">gaseous</a> fuel, low-<a href="/facts/Energy/wd8PrQM7">energy</a> <a href="/facts/Combustion/ohQoWj8z">ignition</a>, wide range of combustible fuel-air mixtures, <a href="/facts/Buoyancy/9dIQwlrh">buoyancy</a>, and its ability to <a href="/facts/Hydrogen_embrittlement/J3JCu2Y6">embrittle metals</a> that must be accounted for to ensure safe operation.
<a href="/facts/Liquid_hydrogen/Vpk3Gb8P">Liquid hydrogen</a> poses additional challenges due to its increased <a href="/facts/Density/92p6hh9I">density</a> and the extremely low <a href="/facts/Temperature/QyGe4gmj">temperatures</a> needed to keep it in liquid form. Moreover, its demand and use in industry—as rocket fuel, <a href="/facts/Hydrogen_economy/TNdU0eR2">alternative energy storage source</a>, <a href="/facts/Coolant/531hqfUQ">coolant</a> for <a href="/facts/Hydrogen-cooled_turbo_generator/8N9tzJDu">electric generators in power stations</a>, a feedstock in industrial and chemical processes including <a href="/facts/Haber_process/DMlVT2WP">production of ammonia</a> and <a href="/facts/Methanol/EIfpoNCg">methanol</a>, etc.—has continued to increase, which has led to the increased importance of considerations of safety protocols in producing, storing, transferring, and using hydrogen.
Hydrogen has one of the widest explosive/ignition mix range with air of all the gases with few exceptions such as <a href="/facts/Acetylene/yaDh6cmJ">acetylene</a>, <a href="/facts/Silane/XNevDLgE">silane</a>, and <a href="/facts/Ethylene_oxide/4WDVKX2r">ethylene oxide</a>, and in terms of minimum necessary ignition energy and mixture ratios has extremely low requirements for an explosion to occur. This means that whatever the mix proportion between air and hydrogen, when ignited in an enclosed space a hydrogen leak will most likely lead to an explosion, not a mere flame.
There are many codes and standards regarding hydrogen safety in storage, transport, and use. These range from federal regulations, ANSI/AIAA, NFPA, and ISO standards. The Canadian Hydrogen Safety Program concluded that hydrogen fueling is as safe as, or safer than, <a href="/facts/Compressed_natural_gas/tMsYjxMK">compressed natural gas</a> (CNG) fueling,

Hydrogen safety open-in-new

Hydrogen safety