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gransolo12
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[*] posted on 27-7-2023 at 09:52
getting rid of hydrogen gas


hi everyone,

what is the best way to get rid of hydrogen gas without being outside? (i.e. being indoors).

for example, what sort of fan and filter would be effective?

thanks for any help
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[*] posted on 27-7-2023 at 10:00


If it is (fairly) pure, not with oxygen mixed in, then the easiest way of getting rid of it is burning it. If the flow is too low to sustain a flame, then you can lead it into a small flame of a gas burner, or a candle flame.

If the amount is very limited (e.g. 1 liter of gas or less), then simply let it disperse in the air. It is non-toxic, and when a liter of hydrogen is diluted over a few cubic meters of air, then there is no risk of fire anymore.

If the hydrogen gas is mixed with air or other oxygen containing gas mixes, and the amount of gas is large, then things get more difficult. Igniting the gas then is not wise at all. In that case I hardly see any other practical option than dispersing the gas in the air, while having very good ventilation (door open, windows open, having a decent air flow, forced by wind).




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[*] posted on 27-7-2023 at 11:18


"....what sort of fan and filter would be effective?"

Gransolo you are going to blow yourself up, and everyone else in the building, if you start venting hydrogen gas from an enclosed room with a fan. Moreover, you will be violating the building code, the fire code, the electrical code, your insurance policy, and a million other things. All the codes have very specific provisions with respect to flammable and explosive materials. Electric motors and electrical connections generate sparks, and special equipment has to be used. You also have to consider static electricity build-up and possible discharge. The International Electrical Code requires special NEMA 7 explosion-proof components, as used in gas stations for example. If you fill exhaust duct with H2 gas and it explodes, you can say goodbye to your arms and legs. Even a small quantity of hydrogen, like a balloon full, will explode with tremendous power. I would not even f__ around with this idea. If you're trying to vent hydrogen from a battery installation, or set up some kind of hydrogen-power facility, you need to get some help from a licensed engineering contractor, and/or a licensed electrical contractor that knows something about alternative-energy facilities.

Woelen is right, just dilute the stuff in the air and get it out of the building, and if you can't then move your equipment to a different space.
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[*] posted on 27-7-2023 at 15:01


"what is the best way to get rid of hydrogen gas without being outside?"
Burp
https://www.frontiersin.org/articles/10.3389/fphys.2020.0106...

Seriously, how much hydrogen?
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[*] posted on 27-7-2023 at 16:54


I am struggling to think of a situation where you are producing enough hydrogen for it to be a problem.
Dispersion should be quick and simple. Pipe it outside if you are worried.


(I do seriously wonder when people start talking about powering vehicles with green hydrogen. The logistics at that scale are really problematic. I doubt anyone has properly thought that through.)
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[*] posted on 28-7-2023 at 00:50


Very broad question. Scale is everything

Industry application
In a battery room for a large UPS system. About 300 12v car battery are being maintained (charged).
A venturi style air blowers is used to remove dangerous gases from the room.
Short version: the hermetically sealed room is maintained at slightly less than atmospheric pressure, air is vented in at specific locations, exhaust is vented out at others, and special methods are used to directly collect any gasses before they can diffuse into the rooms a atmosphere

The blower/motor is not exposed to the hazardous atmosphere, it is setup before the waste gas intake.
Its not very efficient, but is very effective.
Special vents are built into the shelfing that holds the batteries, designed to better collect any gases produced, and prevent them from diffusing into the room.

Strict rules are in place about the amount of air entering/leaving the room at any given moment, monitoring of explosive gases, appratus/component faults. And fire suppression systems/composition. Your normal household fire extinguisher can make certin types of fire worse. Always use the right tool for the right job.

Home chemists application
Perform your reaction in a sealed appratus with a vent line, leading to a flash back suppressor(big bubble jar), and vented outside.

[Edited on 28-7-2023 by Rainwater]




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gransolo12
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[*] posted on 28-7-2023 at 13:48


thanks for all the replies.

the original idea was to have an enclosed 500ml RBF that is half way full with a hose attached that leads to outside a window.

but for example how much h2 would be given off by around 10g of sodium borohydride during a reduction?
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[*] posted on 28-7-2023 at 14:08


Even if the reaction is performed in a very inefficient way, then with 10 grams of NaBH4 I do not expect more than a few liters of H2 gas. Avoid acidic conditions.



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gransolo12
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[*] posted on 28-7-2023 at 16:31


Quote: Originally posted by woelen  
Even if the reaction is performed in a very inefficient way, then with 10 grams of NaBH4 I do not expect more than a few liters of H2 gas. Avoid acidic conditions.


ok, thank you. if the reaction were to give off larger amounts of h2 gas thus requiring lots of ventilation, then what type of filter and fan should be used?

i'm stuck because hepa filters are for particles and activated carbon doesn't really absorb hydrogen gas apparently. and i can't find any good explosion proof fans that don't cost too much.
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[*] posted on 28-7-2023 at 17:04


Why are you trying to filter?
Hydrogen will go through anything.

Simply add a hose to your system and vent outside.
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[*] posted on 28-7-2023 at 17:06


You will not be able to filter H2 gas out of an air stream (to my knowledge) .
It's simply too small of a molecule.

For safety, you want to prevent oxygen and halogens from entering your appratus.
A simple bubbler will do this.
It will also let you see the amount of gas being produced.

A venturi fan would be the safest and have the longest service life.

A venturi fan works exactly like a water asporator.
Placing the fan before any hazards,
not exposing it to exhaust gasses,
keeps it safe and out of harms way.

They are easy to set up and their method of operation can be better explained here
https://en.m.wikipedia.org/wiki/Venturi_effect

You can make one of out paper towel tubes, duck tape and any fan




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gransolo12
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[*] posted on 29-7-2023 at 04:27


i haven't heard of a venturi fan so i'll look into it.

i'm only going to produce very small amounts of h2 gas at the moment, but what apparatus would a professional lab use to deal with very large amounts of h2 gas that is produced by using many kg's of sodium borohydride?

because i assume there's an indoor setup applicable to professional labs that would apply to even a small scale production of h2 gas.
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[*] posted on 29-7-2023 at 08:55


"...but what apparatus would a professional lab use to deal with very large amounts of h2 gas that is produced by using many kg's of sodium borohydride?... because i assume there's an indoor setup applicable"

If you are venting/exhausting "very large amounts" of H2 gas in a building occupied by people, you need to comply with the building code, the electrical code, the mechanical code, the fire code, OSHA, and a rash of Federal State and Local laws pertaining to safety and the built environment. You are on a blog asking synthetic organic chemists how to design and construct a complicated chemical process facility, on a website called "science madness". There is no "setup" that you can slap-in. You hire licensed, insured, engineering professionals to design such a facility, and you hire a licensed, bonded, engineering contractor to build it.

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[*] posted on 29-7-2023 at 09:21


For test tube scale
https://www.youtube.com/results?sp=mAEA&search_query=Hyd...




CAUTION : Hobby Chemist, not Professional or even Amateur
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[*] posted on 29-7-2023 at 10:13


Quote: Originally posted by Johanson  
"...but what apparatus would a professional lab use to deal with very large amounts of h2 gas that is produced by using many kg's of sodium borohydride?... because i assume there's an indoor setup applicable"

If you are venting/exhausting "very large amounts" of H2 gas in a building occupied by people, you need to comply with the building code, the electrical code, the mechanical code, the fire code, OSHA, and a rash of Federal State and Local laws pertaining to safety and the built environment. You are on a blog asking synthetic organic chemists how to design and construct a complicated chemical process facility, on a website called "science madness". There is no "setup" that you can slap-in. You hire licensed, insured, engineering professionals to design such a facility, and you hire a licensed, bonded, engineering contractor to build it.



i wouldn't vent 'very large amounts of h2' in a building, this isn't what i'm doing at the moment. the 'very large amounts of h2' i'm asking about is a hypothetical question (which wouldn't be done in a residential building). i'm asking this hypothetical to gain a better understanding of what is needed for hydrogen gas safety.
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[*] posted on 29-7-2023 at 12:53


Large scale industry will purify the H2 gas then pipe it into another process
Smaller industries, dilute the gas far below its explosive limit and exhaust it into the atmosphere.

In eather case, gas is accumulated in tanks called gasometers before processing.
https://en.m.wikipedia.org/wiki/Gas_holder

Quote: Originally posted by Johanson  
"There is no "setup" that you can slap-in. You hire licensed, insured, engineering professionals to design such a facility, and you hire a licensed, bonded, engineering contractor to build it.

Amen
storage of any amount of H2 should be delt with seriously.
It is the very definition of explosive.

20+ years building stuff for nerds with money
houses to highrises, manufacturing to synthesis facilities. Unclassified to Class(I) division(I) and FEML compliant




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[*] posted on 29-7-2023 at 13:54


yes i wouldn't store any h2.

how is the h2 purified?
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[*] posted on 29-7-2023 at 19:54


Distillation



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gransolo12
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[*] posted on 30-7-2023 at 04:15


would diluting the area where h2 gas is with argon or nitrogen in equal parts reduce its explosiveness and flammability?
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[*] posted on 30-7-2023 at 04:55


Quote: Originally posted by gransolo12  
i'm only going to produce very small amounts of h2 gas at the moment, but what apparatus would a professional lab use to deal with very large amounts of h2 gas that is produced by using many kg's of sodium borohydride?
No “lab” uses “many kg of sodium borohydride.” That is no longer lab scale, that is factory scale. Process chemistry. As others have mentioned, different rules apply in that scenario, and facilities that need to likely have unique ways of dealing with it.

Quote: Originally posted by gransolo12  
because i assume there's an indoor setup applicable to professional labs that would apply to even a small scale production of h2 gas.
That’s called a fume hood, you may have heard of it.



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[*] posted on 30-7-2023 at 06:22


Quote: Originally posted by gransolo12  
would diluting the area where h2 gas is with argon or nitrogen in equal parts reduce its explosiveness and flammability?

If you dilute the hydrogen with air until it is below 4% it is no longer flammable.
Air is cheap.

If you have an experiment which might produce 20 litres of hydrogens over the course of 5 minutes then you need to be sure that you dilute it with a lot more than (25 X 20) /5 litres of fresh air per minute.
That isn't difficult.
Once the gas is dilute enough, you no longer need an explosion proof fan.

It's also sensible to not have any source of ignition nearby.
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[*] posted on 30-7-2023 at 11:16


As an aside I did a flow reaction involving a coupling that generated hydrogen as a by-product. Because Le Chatelier's principle was working against me (my reaction was run under significant pressure) with hydrogen as a by-product I had to find a way to get rid of it without releasing the pressure on the system. Enter the gas specific membrane. There were two membranes trialed, one was a semi-permeable membrane made of hydrophobic material, a bundle of small tubes passed through an outer tube under vacuum. This allows quick to diffuse molecules like hydrogen to make their way out. Problem was I was losing solvent though pervaporation as well.

I ended up using a trick from the oil industry using a molecule specific membrane, palladium. This allows hydrogen to effuse but nothing else. Works like a charm if you've got money in the bank.




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[*] posted on 31-7-2023 at 11:18


Quote: Originally posted by Texium  
Quote: Originally posted by gransolo12  
i'm only going to produce very small amounts of h2 gas at the moment, but what apparatus would a professional lab use to deal with very large amounts of h2 gas that is produced by using many kg's of sodium borohydride?
No “lab” uses “many kg of sodium borohydride.” That is no longer lab scale, that is factory scale. Process chemistry. As others have mentioned, different rules apply in that scenario, and facilities that need to likely have unique ways of dealing with it.

Quote: Originally posted by gransolo12  
because i assume there's an indoor setup applicable to professional labs that would apply to even a small scale production of h2 gas.
That’s called a fume hood, you may have heard of it.


ok. i haven't seen much info on process chemistry.

yes i know about a fume hood, but i hoped there might be a cheaper product that does the same thing. and i can't find out exactly what type of filter is used for hydrogen gas in a fume hood.
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[*] posted on 31-7-2023 at 11:28


Quote: Originally posted by unionised  
Quote: Originally posted by gransolo12  
would diluting the area where h2 gas is with argon or nitrogen in equal parts reduce its explosiveness and flammability?

If you dilute the hydrogen with air until it is below 4% it is no longer flammable.
Air is cheap.

If you have an experiment which might produce 20 litres of hydrogens over the course of 5 minutes then you need to be sure that you dilute it with a lot more than (25 X 20) /5 litres of fresh air per minute.
That isn't difficult.
Once the gas is dilute enough, you no longer need an explosion proof fan.

It's also sensible to not have any source of ignition nearby.


so maybe just having a fan blowing lots of fresh air into the work area might be enough?

once sodium borohydride has been added to a solvent such as ipa, does it produce hydrogen gas in a short burst, or over a prolonged period?
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[*] posted on 31-7-2023 at 11:54


Quote: Originally posted by BromicAcid  
As an aside I did a flow reaction involving a coupling that generated hydrogen as a by-product. Because Le Chatelier's principle was working against me (my reaction was run under significant pressure) with hydrogen as a by-product I had to find a way to get rid of it without releasing the pressure on the system. Enter the gas specific membrane. There were two membranes trialed, one was a semi-permeable membrane made of hydrophobic material, a bundle of small tubes passed through an outer tube under vacuum. This allows quick to diffuse molecules like hydrogen to make their way out. Problem was I was losing solvent though pervaporation as well.

I ended up using a trick from the oil industry using a molecule specific membrane, palladium. This allows hydrogen to effuse but nothing else. Works like a charm if you've got money in the bank.


that's interesting. i haven't heard of that. are there any references/papers you could tell me about that go into more detail?
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