Hydrogen in the mix...

[Externet]

Stumbled upon this; move or delete if improper. Prefer to share than hide.

----> The first deep rebreather dive using hydrogen: case report - PubMed

 

[SpaceX Aquanaut]

How do you go about safely home blending this “cheap & plentiful Diluent?”:

“Hydrogen's flammability range (between 4% and 75% in air) is very wide compared to other fuels; Under the optimal combustion condition (a 29% hydrogen-to-air volume ratio), the energy required to initiate hydrogen combustion is much lower than that required for other common fuels.

If hydrogen gas mixtures enter confined regions, ignition is very likely and can result in flame acceleration and generation of high pressures capable of exploding buildings and throwing shrapnel. Flammable mixtures of hydrogen in confinements such as pipes or ducts, if ignited, will readily result in accelerated flames and conditions that can lead to detonation.

A leak in a pressurized (>200 psia) hydrogen storage system will result in a jet that may extend for some meters. If ignited, the jet flame can cause serious damage to anything it encounters.”

 

[Mobulai]

Thread from original author of the pub:

Thread 'Report on first deep hydrogen dive using a rebreather'

Mar 31, 2024

Hello,

This subject has come up in a few threads elsewhere, but the 'official' (peer reviewed) report on the hydrogen dive performed by Richard Harris in the Pearse Resurgence last year was published yesterday in Diving and Hyperbaric Medicine Journal. I have attached the paper here.

Harris RJ, Challen CJ, Mitchell SJ. The first deep rebreather dive using hydrogen; case report. Diving Hyperb Med. 2024;54(1):69-72. doi: 10.28920/dhm54.1.69-72. PMID: 38507913.

Simon M

• Dr Simon Mitchell
• Replies: 19
• Forum: Rebreather Diving

• 

And on initial dive:

Thread '1st deep (750 ft) hydrogen CCR dive: Gateway to deep exploration?'

Nov 29, 2023

Simon Mitchell takes us back to New Zealand's Pearse Resurgence with Richard “Harry” Harris & the Wet Mules. Really interesting physiological & logistics/gear details.
~250 meters, 16 hours, 6°C…

"In February 2020 the Wet Mules diving team pushed the Pearse Resurgence cave to 245m. Further progress required overcoming the high-pressure neurological syndrome [HPNS] and reducing respired gas density. The solution to both problems would be a light and slightly narcotic gas; properties possessed by hydrogen. In February 2023 the team successfully tested hydrogen in a rebreather dive to 230m...

• kimh
• Replies: 9
• Forum: Diving Physics, Physiology, & Medicine

• 
• 

 

[Capt Jim Wyatt]

Hydrogen? Sounds like a death wish to me.

 

[Kendall Raine]

Hydrogen? Sounds like a death wish to me.

Jim;

They're experimenting with hydrogen to go deeper than 245m. In a real cave, not a sink hole. 30 min BT. 12C. Seems like the hydrogen is the least of their worries

 

[SpaceX Aquanaut]

Well . . .how about bringing my doubles to one of those Hydrogen Fill Stations for Fuel Cell Cars?

 

[Mobulai]

Well . . .how about bringing my doubles to one of those Hydrogen Fill Stations for Fuel Cell Cars?

If you got a compatible whip.. why not

(I’d be interested to f around and find out since the current experiment sample is at n=1; but no way I’m doing it in the same conditions )

 

[lowwall]

How do you go about safely home blending this “cheap & plentiful Diluent?”:

“Hydrogen's flammability range (between 4% and 75% in air) is very wide compared to other fuels; Under the optimal combustion condition (a 29% hydrogen-to-air volume ratio), the energy required to initiate hydrogen combustion is much lower than that required for other common fuels.

You don't. The Limiting Oxygen Concentration for a mix of H, N and O is 5%. I'm not sure what the LOC for a H, He, O mix, but presumably it's above the 4% maximum O2 (hypoxic) helihydrox mix used in the actual dive,

Limiting oxygen concentration - Wikipedia

en.wikipedia.org

[edited - I originally had "normoxic" in there, I keep mixing up (get it?) the terms normoxic and hypoxic. Good thing I'm not a tech diver.]

 

[SpaceX Aquanaut]

You don't. The Limiting Oxygen Concentration for a mix of H, N and O is 5%. I'm not sure what the LOC for a H, He, O mix, but presumably it's above the 4% maximum O2 (hypoxic) helihydrox mix used in the actual dive,

Limiting oxygen concentration - Wikipedia

en.wikipedia.org

[edited - I originally had "normoxic" in there, I keep mixing up (get it?) the terms normoxic and hypoxic. Good thing I'm not a tech diver.]

And all you need attempting a home blend with Hydrogen is Electro-Static Discharge:

 

[lowwall]

No one is proposing it for general purpose use.