Why Can't We Detect Hydrogen with IR Sensors in Explosion-Proof Areas?

[Aya ElElbshihy]

Hi all
My mainly question is about why we won't be able to detect Hydrogen as Ex. gas using IR technology sensors?
Also, I'd like to know if H2 would be detected using IR senosor?
I need to know what is the equivalent technology for this purpose too?
Thanks
Ay ElEbshihy

 

[DrClaude]

I don't really understand all you are saying (what is an "Ex. gas"?), but I can tell you that H₂ is transparent in the infra-red.

 

[mjc123]

To be more specific, when a homonuclear diatomic molecule like H₂ vibrates, there is no change in dipole moment, therefore nothing for an oscillating electric field (EM radiation) to couple with to cause absorption. So H₂ doesn't absorb infrared radiation. (The same is true of O₂ and N₂, which is why we don't have a runaway greenhouse effect.)

 

[Aya ElElbshihy]

I don't really understand all you are saying (what is an "Ex. gas"?), but I can tell you that H₂ is transparent in the infra-red.

1st thank you for your reply
I mean in an Explosion proof area like petroleum sector companies
You explained that H2 is transparent in the IR so what is the another solution to avoid this point
Thank you

 

[Aya ElElbshihy]

To be more specific, when a homonuclear diatomic molecule like H₂ vibrates, there is no change in dipole moment, therefore nothing for an oscillating electric field (EM radiation) to couple with to cause absorption. So H₂ doesn't absorb infrared radiation. (The same is true of O₂ and N₂, which is why we don't have a runaway greenhouse effect.)

1st thank you for your reply
What is the another solution to avoid this point
Thank you

 

[DrClaude]

It shouldn't be hard for you to google "hydrogen gas detector"

 

[Nik_2213]

IIRC, there's two temperature sensitive resistances, one coated with a catalyst, run side-by-side in a bridge arrangement. Catalysed, any hydrogen reacts with ambient oxygen, alters its leg's temperature and resistance, unbalances the bridge...

Similar tech checks for 'general flammable vapour', such as methane etc and toxic gas such as Carbon monoxide. But, because such are less responsive to ambient catalytic oxidation, they may need to be warmed. Think how car exhaust catalysers don't work well until hot enough...

The extra circuitry and protocols for self-testing and maintenance of such safety-critical equipment is well beyond my amateur reading.

FWIW, some of our hydrogen-flame GCs had an internal leak sensor, which had to be replaced at service intervals as air pollution progressively poisoned the active surface.

Um, also Google 'Faraday Lamp'...

 

[Astronuc]

1st thank you for your reply
I mean in an Explosion proof area like petroleum sector companies
You explained that H2 is transparent in the IR so what is the another solution to avoid this point
Thank you

Honeywell makes a variety of gas sensors, including sensors for hydrogen. Catalytic and electrochemical sensors are used to detect hydrogen, and they require oxygen.
See Chapter 10, starting on page 36, and see Table on page 43 in
https://www.honeywellanalytics.com/~/media/honeywell-analytics/documents/english/11296_gas-book_v5_0413_lr_en.pdf?la=en-gb