Most common odorants will contaminate fuel cells. Additionally, hydrogen's small molecule and high buoyancy make it challenging to find a compatible odorant. Research is being conducted on fuel cell compatible odorants, but there are none currently in use. Like liquefied natural gas, liquid hydrogen also can’t be odorized due to its cryogenic temperature.
Hydrogen flames can be nearly invisible in daylight, especially at low flowrates. The concentration of hydrogen does not have much effect on the color of the flame. Many hydrogen incidents or fires will have a bright orange hue, or even yellow flames. The color is primarily caused by contaminants that is either naturally in the air in certain environments, swept into the air during the release…
Yes, small flowrate vents may be invisible, particularly in daylight. Sometimes it may still be possible to see heat striations in the air from the heat generated by the fire, but it can be difficult to discern at low flowrates.
The “Hydrogen Ready Appliances Assessment Report” published by the Northwest Energy Efficiency Alliance (NEEA) in February, 2023, is one of the most recent studies on this topic. Several key items from the report pertaining to this question include the following:
1. “There appears to be growing consensus that blends of up to 20% or perhaps even 30% are…
Many methods are used to mitigate the risk of a tube trailer hose loss of containment incident. Examples that otherwise exceed code requirements are provided below. These have been deployed in various combinations depending on the risk analysis for a particular system:
A "drop and swap" delivery system using tube trailers is a common and accepted method of supply for both industrial and fueling station applications. While NFPA 2 - 2023, paragraph 10.6.3.5 states, "The use of hose in a hydrogen dispensing system shall be limited to vehicle fueling hose," this is intended for the dispenser itself, not the entire fueling station. This does not limit the use of…
A design condition for vent stacks is to always assume that the hydrogen will ignite. The stack musts be designed such that it can withstand those conditions as well as minimize radiation to surrounding personnel and exposures. Although hydrogen fires have comparatively low radiation compared to hydrocarbon fuels, the radiation from large releases from vent stacks can be quite high. Documents…
The purity required will be a function of the end use application. There are a variety of grades of hydrogen that can be purchased. The H2 purity will also vary based on source (GH2 or LH2) and production method. CGA G-5.3, Commodity Specification for Hydrogen, lists several typical purities of both liquid and gaseous hydrogen. Standard GH2 available from most suppliers is 99.95% hydrogen.…
Gaseous hydrogen can be stored forever as long as the system integrity is maintained. However, liquid hydrogen is “use it or lose it” and will boil from system heat leak and build pressure unless it is used or vented. This is not usually an issue for continuous use or low-pressure applications which can use hydrogen gas pressure directly from the tank.
For intermittent or high…
Yes, although not as common as high-pressure gas releases, high-velocity cold H2 gas has ignited during rupture disc and relief valve activation.
We are the leaders in the building industries and factories. We're word wide. We never give up on the challenges.