My concern is much less on the input side as the high humidity does reduce static discharge potential as Eugene explains. The output side, however, is into room air.  These devices can be used for “at-home” patients and that introduces a poorly ventilated, uncontrolled setting.

I hope these do not become common in USA/EU

All:

I have written to the journal’s EIC and pointed out the safety hazard. I asked why the published manuscript did not address safety and requested the EIC to review and respond.

I will post the response, if any, whenever received.

nl

Interesting. I have written an article on the history of explosive gas mixtures like this that is about 80% finished. It has incident history for over 30 incidents with mixtures like this made by accident, deliberately or system failure. The most dangerous point when handling these mixtures is when the cylinder valve is opened. This can create adiabatic compression heat that will ignite the mixture and backflash into the cylinder. I investigated the Dec 2018 incident in India where they were using a 66%H2/O2 mixture to fill a shock tube chamber. It had 1800 psig when it exploded. Cut the operator in half and threw the top of his body 20 ft away and ripped the bottom half into pieces. Found his wrist watch on the roof about 40 high.

I have an article “Dangerous Gas Mixtures” that speaks about these in some detail. You can download it from my website under files. There was a guy that was selling mixtures like this for fuel cell research. He had 3 explosions that he blamed it on defective cylinders and continued. He finally had a 4^th explosion that crippled his son and they closed him down. You can read about it in the article. It has been proven that explosive gas mixtures like this can be physically handled and transported long distances without ignition.

Since they are mixing it at atmospheric pressure adiabatic compression is not a source of ignition. If they humidify it, static will not be a source of ignition. The potential for ignition is pretty remote.

Similar to this, acetylene is an excellent anesthetic. Time Magazine March 31,1923 reported 500 operations using 40 % Acetylene & 60 % Oxygen scented with pine oil. They must have had problems since it was discontinued in 1925. I would love to get my hands on that article.

Did you know

1. The first recorded use of hydrogen as a breathing mix was in 1789. Lavoisier (The Father of Modern Chemistry) and Sequin exposed guinea pigs to mixtures of hydrogen and oxygen (Hydrox). They observed that the animal's oxygen consumption appeared to be similar in hydrogen/oxygen as in nitrogen/oxygen.
2. Deep sea divers use a 5% O2/H2 mixture which is not explosive.
3. TRW has a patent on an high pressure explosive H2/O2 mixture to inflate airbags. The advantage was the byproduct is water and the mixture is stable. The other advantage was that a weight sensor would determine the amount of inflation required. The squib would be fired at different locations in the cylinder. DOT required them to do hundreds of tests to demonstrate that it was safe to ship. Bullet penetration, drop impact, etc
4. After 9/11, the FAA prohibited oxygen cylinders form being brought onto a plane because it can be filled with a 66%H2/O2 mixture that the person could breath. Once on the plane it becomes an IED. They need to rent a cylinder from the airline
5. Nitric oxide is a highly toxic gas with a LC50 of 115 ppm. Ikara has a billion $$$ business treating premature infants with a 20 ppm mixture for 24 hours. They were also using it for COVID treament

Eugene Ngai

Chemically Speaking LLC

www.chemicallyspeakingllc.com

Hi all,

A colleague of mine came across the following study when searching for some H2/O2 safety data. We’re rather shocked that someone is administering a 2:1 mix of hydrogen and oxygen to patients via nasal cannula. Having zero background in medicine, I have no idea whether breathing explosive mixtures is a common practice, but the chemist in me says this is an explosion (inside the respiratory tract!) waiting to happen. Any thoughts? Is this as insane as I think it is?

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7330772/

Timothy J. Kucharski, PhD

Senior Engineer

Electric Hydrogen

Move Fast and Break Bonds

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