Excess flow shut off valves are always prudent although a properly sized restrictive orifice can also be just as safe. (It also usually allows a smaller size relief device.

 

While hydrogen can embrittle metals, the line of pure hydrogen regulators is measured in decades. Usually the diaphragm fails long before any other component sees any issues. We finally stopped inspection hydrogen regulators after 20 years of data and found that while an occasional diaphragm failed unexpectedly,  the RO and relief device provide adequate protection.

 

You might want to look at these for more information

 

Compressed Gases: Managing Cylinders Safely (Chemical Engineering, Oct 2009)

Compressed Gas Cylinder Safety In Research Applications, https://www.linkedin.com/pulse/compressed-gas-cylinder-safety-research-applications-richard-palluzi/

 

The AICHE publication   Handbook for Process Safety in Laboratories and Pilot Plants, (Wiley, 2023) also has a good section on the hazards of compressed gases and how to avoid them.

 

 

From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU> On Behalf Of Margaret Rakas
Sent: Friday, February 21, 2025 10:18 AM
To: DCHAS-L**At_Symbol_Here**Princeton.EDU
Subject: [DCHAS-L] Hydrogen Gas Safety

 

Good morning-

 

We have 3 different cylinders of hydrogen in use in one lab (different grades for different pieces of equipment ) and have the following questions (I've searched the web but am not sure what is done with relatively small amounts of hydrogen versus a lab that has higher number in use or a 'tank farm' setup.

 

1) Do you routinely use excess flow shutoff valves?  We do have flame arrestors in line with each regulator....

 

2) How long are regulators (for inert gases as well as hydrogen) used before refurbishing or replacement?  Apparently hydrogen gas can embrittle metals...

 

3) If you send them out for refurbishment I would be interested in knowing where, and how you know their initial age?

 

thanks very much!
Margaret

 

--

Margaret A. Rakas, Ph.D.
Lab Safety & Compliance Director
Clark Science Center

Smith College
413-585-3877 (p)

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