It depends on the facility and risk assessment, but generally multiple pressure and temperatures to one vent stack is not the best practice unless all are similar in pressure and temperature, and the streams have compatible composition and flow rate. Care must also be taken to prevent reverse flow and misdirected flow between portions of the system. Additionally, one vent stack can become a…

Requirements for local jurisdictions vary, so the AHJ should be consulted, but NFPA 2:2023, Hydrogen Technologies Code, Chapter 13 has requirements for installation of hydrogen generators up to 100 kg H2/h. Section 13.3.1 General says permitted water electrolysis systems are to be listed to ISO 22734:2019, Hydrogen Generators Using Water Electrolysis - Industrial, Commercial, and Residential…

Cylinders are required to be tested periodically to verify structural integrity. The most common test method is hydrotesting, which means water is the most likely impurity that solidified in the inlets. Drying the tanks is normally a requirement after performing a hydrotest. In the USA, CFR 49 CFR § 180.209 applies: https://www.law.…

The end use of hydrogen usually drives the cleaning for initial construction. 

1. When the hydrogen is used for combustion and many industrial applications, normal care during construction and leak testing is usually adequate.
2. When the hydrogen needs to be very pure, as is the case for PEM fuel cell applications, more…

Because hydrogen is labeled as a hazardous substance, sometimes people are concerned about the environmental impact of releasing liquid hydrogen. There are currently no regulations that require reporting of hydrogen releases for environmental reasons.

However, there are safety implications. For example, the US DOT requires reporting of hazardous materials releases under certain…

Purging of vent systems is not required and in most instances is not recommended.

A nitrogen purge is generally not needed for a vent system designed in accordance with CGA G-5.5.  However, there are times where this might be considered or required due to the specific design of a system.  Where determined by a risk review to be needed, A continuous purge into a vent system…

Catalytic recombiners are effective at preventing flammable hydrogen mixtures and also sometimes useful to monitor hydrogen concentrations through heat evolution when an oxidizer is present. Careful considerations must be made when integrating these elements into a design, so that they do not become a source ignition (and/or flame arrestors prevent propagation of a flame front) and the…

Off gassing of hydrogen from battery sources depends on battery chemistry, usage/duty cycle, age, and other considerations. The specific battery manufacturer should provide recommendations for fire prevention and mitigation in battery charging rooms as the battery itself impacts how an event would be mitigated. Adequate ventilation such that combustible mixtures cannot develop is a general…

Typically, the inner vessel material used is 304 SS and the outer vessel is a combination of 304 SS and carbon steel depending on location. 316 SS or 316L material can be used, but due to higher cost and lower strength, are typically only used for higher purity systems. Nearly all tanks manufactured today use various forms of vacuum jacketed multilayer insulation for best performance. Older…

The most common means to warm liquid or cold gaseous hydrogen is the use of ambient air vaporizers using ambient atmospheric. Other means can be through the use of electric heat or process waste heat.