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In the case of fuel-rich mixtures like those in the question, the heat of combustion for the mixture should be calculated on the basis of the oxygen content of the mixture. The heat of combustion per mole oxygen is twice the heat of combustion per mole hydrogen, i.e., it is 286*2 kJ per mole O2. You should be able to do the calculations based on this reply.
There are no specific code resources that specifically cover hydrogen liquefaction plants, but they must be built to the general building, electrical, machinery, piping, and mechanical codes for process plants. Codes such as NFPA 2, Hydrogen Technologies Code, for installation and emergency response may also be used for reference. It may also be beneficial to break down the requirements into…
The regulations for electrical classification in Europe and a US jurisdiction such as California are significantly different and should not be assumed to be the same. Consultation with Authorities Having Jurisdiction or a Third- Party expert regarding the application of the US National Electric Code is advised. Some additional important points:
The HSP has concerns with the use of…
The British Standards Institute (BSI) has published BS ISO 22734:2019, a British nationalized version of the packaged water electrolyzer safety certification standard. This standard can be used by a Notified Body (BSI is one of many operating in the UK and in Europe) to certify electrolyzer safety to established norms for this equipment. This standard addresses safety of containerized hydrogen…
The vent system for the excess hydrogen should be vented in accordance with NFPA 2 and CGA G-5.4 and G-5.5. The oxygen also must be vented safely and should be in accordance with NFPA and CGA G-4.4.
Please be extremely cautious with compressing hydrogen. NEC/NFPA 70 and its Articles 500/505 address electrical equipment in flammable atmospheres. Please also consider the…
Regarding cylinders, it is not necessary to capture the fuse-backed devices which are on the cylinder itself. However, all other relief devices and vent valves must exhaust from a vent system designed in accordance with CGA G-5.5. Also, note that NFPA 2-7.1.17 requires compliance with CGA G-5.5 regardless of storage quantity when the vent system is servicing pressure relief devices. Cylinders…
Panel members have not encountered a device or area classification for ATEX approval within Canada. ATEX is a European Union directive and is not generally recognized within North American standards. The second link below references a UL similarity. https://news.nilfiskcfm.com/2017/03/atex-certification-applicable-north-america/; https://www.ul.com/services/atex-certification-…
NFPA 2 has provisions for the use of LH2, and there are many existing fueling stations that store and use liquid hydrogen. One challenge for the use of LH2 in stations with small footprints is the code required separation distances from exposures. NPFA 2 has updated the separation distances with a risk informed approach in the 2023 edition.
Another possibility for public fuel…
This is not an easy question since many factors influence how much hydrogen can be transferred from one vessel at a higher pressure to another one at a lower pressure and the rate at which it can be transferred. The pressure in the higher vessel will fall while that in the lower vessel will rise as gas is transferred, so the flow rate will typically slow down and eventually stop as the…
It varies slightly due to different density of LH2 at different temperatures, but a gallon of LH2 at atmospheric pressure (0 psig) is ~113 SCF of H2. The expansion ratio is about 840:1. In metric units, a liter of LH2 at atmospheric pressure (0 MPa) would expand to about 840 liters of STP of gaseous pressure.
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