Hydrogen Safety for the Industry

Unlike actual explosives, pure hydrogen cannot explode. The risk comes when it hits the air. For hydrogen to cause an explosion, oxygen needs to be present. But if hydrogen is allowed to escape, even a static spark from clothing would be enough to set off an explosion.

Hydrogen burns with a very pale flame that is invisible in daylight. Because it emits little of the infrared radiation that humans perceive as heat, it cannot be sensed as heat. A hydrogen flame does however emit substantial ultraviolet radiation. Special UV detectors are therefore required to alert to the presence of hydrogen flames.

Owing to its small molecules and low viscosity, hydrogen can leak from pipelines and other structures more easily than denser gases. In fact, when it leaks from a pipe at sufficiently high pressure, hydrogen can even self-ignite. As well as pipelines engineered to hydrogen-ready specifications, regular inspection is imperative to detect leak points at joints and along pipelines. Fixed leak detectors add another layer of safety.

Hydrogen can easily permeate materials and in some cases embrittle them. For this reason, stainless steel and composite materials are typically used for storage tanks.

Carbon monoxide (CO) sensors are cross-sensitive to hydrogen. If used near possible hydrogen exposure, CO sensors should be compensated for hydrogen so that cross-sensitivity and false alarms are reduced to a minimum.

Like ammonia and methane, hydrogen is less dense than air and forms gas pockets below indoor ceilings when leaking. The presence of hydrogen will not be perceived at ground level, even when dangerous amounts are accumulating beneath the ceiling. When hydrogen and methane are mixed, hydrogen can form gas pockets above methane. Hydrogen detectors are therefore typically placed at the top, with methane detectors below that level.

Hydrogen has no smell and no colour, so is undetectable for humans. With methane, this issue is mitigated by adding odorants, and research is in progress to determine whether this will also be possible with hydrogen. Gas and leak detectors are essential.