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I'm interested in doing some experiments with electro-chemical machining in my shop. The process involves running electricity through an electrolyte (salt water) to break down a metal anode (aluminum/steel), and it releases hydrogen gas. I'm comfortable with electricity safety, but I have very little chemistry experience, and I'm worried about generating hydrogen in my shop. There's obviously an explosion risk, and I want to understand the safety concerns of what I'm doing.

My research so far has found a lot of high school chemistry experiments, which seem to simply ignore the hydrogen and release it into the room. I will be running processes for hours, so I don't think this is an option for me. I've also found descriptions of large scale industrial processes and proper chemistry labs, both of which use pre-made systems generally out of my reach. Chemical safety datasheets have storage and handling info, but I don't see anything I can use for build guidance.

In the absence of a pre-built lab and fume hood, what is the best practice for dealing with medium amounts of hydrogen gas? Is the answer simply "you need a fume hood"? Can I contain and/or compress the gas and dispose of it safely? If ventilation is the only way, is there any advice/guidance for constructing it within safety guidelines? Ideally I'd love a guide for what materials are safe to use, what's a safe way to vent (if that exists), etc.

Edit: it occurred to me, can I just burn the hydrogen immediately as it's generated? It seems like maybe some kind of contain and combust strategy might make things nice and simple

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    $\begingroup$ Prudent Practices in the Laboratory (National Research Council) has general parameters for what you request. NASA's 389-page tome Safety Standard for Hydrogen and Hydrogen Systems is what I would defer to, as NASA is charged with keeping humans alive in all kinds off adverse environments. Plus, I think 389 pages probably covers all the bases. $\endgroup$
    – Todd Minehardt
    Commented Jan 5, 2022 at 23:47
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    $\begingroup$ This is exactly what I was looking for, thank you so much @ToddMinehardt! $\endgroup$
    – ZECTBynmo
    Commented Jan 6, 2022 at 2:04
  • $\begingroup$ The primary concern for hydrogen in a room is that it can rise to the celling with limited dilution and reach explosive concentrations. $\endgroup$
    – blacksmith37
    Commented Jan 6, 2022 at 18:49
  • $\begingroup$ A fume hood is the most practical way to handle it. We commonly used hydrogen and vented it to atmosphere with laboratory hoods. My first employer ( very long ago) did not have a hood and blew out a large brick wall $\endgroup$
    – blacksmith37
    Commented Jan 6, 2022 at 18:54
  • $\begingroup$ If you know the current, you can accurately calculate the rate at which gas is produced (e.g. in liter per hour). Knowing that number will give you a much better idea about the possible danger, and sensible countermeasures. $\endgroup$
    – Karl
    Commented Jan 15, 2022 at 22:53

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Yes, NASA has good information on Hydrogen Safety.

Here is the key take away, to quote:

Hydrogen has a very broad flammability range—a 4 percent to 74 percent concentration in air and 4 percent to 94 percent in oxygen; therefore, keeping air or oxygen from mixing with hydrogen inside confined spaces is very important.

So, how does one practically stay out of this range, particularly, with small amounts that could tally just over 4%?

The only practical safe answer is a powerful ventilation system. As exactly how one effectively accomplished this is the main question. Perhaps, as hydrogen gas is a very light, one idea suggests the room has a high ceiling which, to a degree, has a fire place like design (noted for safely venting carbon monoxide), complete with a chimney.

Good luck and stay safe.

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