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1.3 Handling Compressed Gas Cylinders
WARNING
Do not handle compressed hydrogen gas cylinders without training or experience.
• Use a pressure regulator to control the fuel inlet pressure to the system.
• Do not alter the fitting on a regulator. Ask experienced personnel for help.
• Do not attempt to force gas cylinder threads.
• Never transport a gas cylinder with regulators attached. Ensure cylinder caps are in
place. Always use a cylinder cart with a safety strap or chain.
• Secure a high-pressure cylinder to a bench, post, or fixed object to avoid accidental
contact.
• Avoid unnecessary contact with On/Off valves. They can easily move to “On” by
accident.
1.4 Hydrogen Leakage
Hydrogen is colourless, odourless and tasteless. Hydrogen is non-toxic but can act as a
simple asphyxiant by displacing the oxygen in the air. There are no warning symptoms
before unconsciousness results.
WARNING
Inhaling hydrogen can lead to unconsciousness and asphyxiation. Hydrogen molecules
are smaller than any other gas, making hydrogen more difficult to contain. It can diffuse
through many materials considered airtight. Fuel lines, non-welded connections, and
non-metal seals such as gaskets, O-rings, pipe thread compounds and packings present
potential leakage or permeation sites. Furthermore, hydrogen’s small molecule size
results in high buoyancy and diffusivity, so leaked hydrogen will rise and become diluted
quickly.
Constant exposure to hydrogen causes hydrogen embrittlement in many materials. The
mechanisms that cause hydrogen embrittlement effects are not well defined. Factors
known to influence the rate and severity of hydrogen embrittlement include hydrogen
concentration, hydrogen pressure, temperature, hydrogen purity, type of impurity, stress
level, stress rate, metal composition, metal tensile strength, grain size, microstructure
and heat treatment history. Moisture content in the hydrogen gas may lead to metal
embrittlement through the acceleration of the formation of fatigue cracks. Hydrogen
embrittlement can lead to leakage or catastrophic failures in metal and non-metallic
components.
As a preventative measure, the stack must be operated in a well-ventilated area in order
to inhibit potential hydrogen accumulation.
WARNING!
Always operate the stack in a well-ventilated area and ensure that ventilation slots are
unobstructed.