Hydrogen Gas Detector

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Joshua Guertler
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Hydrogen Gas Detector

Post by Joshua Guertler » Thu Feb 06, 2020 3:06 pm


I was curious if anyone might have a hydrogen gas detector that they'd be willing to sell or allow me to rent. Unfortunately, most eBay and Amazon offers for hydrogen go for $300, which is far outside of my price range.

It doesn't need to be fancy, just something that'll say if there's a dangerous amount of hydrogen present. Thank you.

Roberto Ferrari
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Re: Hydrogen Gas Detector

Post by Roberto Ferrari » Thu Feb 06, 2020 4:08 pm


Your concern is adecuate.
But keep in mind H2 is very diffusive, so a vented room will assure a non-explosive mixture ratio with air.

Joshua Guertler
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Re: Hydrogen Gas Detector

Post by Joshua Guertler » Thu Feb 06, 2020 4:32 pm


I'm planning to incorporate it into a science fair project. These guys are pretty hydrogen- and radiation-phobic, so I need to do everything in my power to prove to them that the concentration of it at the exhaust of the roughing pump isn't high enough to cause an explosion.

Victor Gonzalez
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Re: Hydrogen Gas Detector

Post by Victor Gonzalez » Thu Feb 06, 2020 5:38 pm

I would use the MQ-8 with an arduino
Hydrogen sensor

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Rich Feldman
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Re: Hydrogen Gas Detector

Post by Rich Feldman » Fri Feb 07, 2020 7:35 pm

I've done plenty of science fair judging, and would be surprised if there's a fair at which you could operate a fusor.
Consider the class of projects that includes rockets, drones, and baseball catchers' masks.
People who have made fusors for science fairs may say otherwise.

How 'bout having a continuous ignition source at the exhaust of roughing pump. :-)

My guess is that to get a standing flame of hydrogen at fusor flow rates (order of 10 sccm ?),
you'd need a pretty small nozzle and good blocking against wind. The flame might be nearly invisible.

As hydrogen displaces air in the roughing pump's oil box, I bet there will be a period when the mixture is explosive. And that if it were to ignite, the maximum overpressure would be too small to damage the pump. Anybody here ever look into that? There must be plenty of industrial vacuum processes where flammable and/or toxic gases are pumped through.

[edit]Don't know how many "regulars" will see this.

Seems to me that in traditional fusor operation,
it's normal that D2-air ratio inside the oil box of roughing pump will be explosive for a while.

The limits for H2-air are about 5% to 75%.
Figure 4 on page 22 of this document: https://www.vtt.fi/inf/julkaisut/muut/2 ... 026_05.pdf
shows p2/p1 ratios as high as about 8, after adiabatic combustion of stoichiometric mixture (about 32% H2).
That would be around 100 psig. I bet a little lower when H2 is replaced with D2.
Maybe enough to pop a rubber exhaust-venting hose off a barbed exhaust fitting.
If there were an ignition source, which seems about as likely as an ignition source inside a gasoline storage tank.
All models are wrong; some models are useful. -- George Box

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