The first deep rebreather dive using hydrogen: a gateway to deep exploration? - Simon Mitchell

Great to see people pushing boundaries, i recall ida-73 kicking on ebay few years back, was tempted to buy it, but spent all cash on boris. So looks like Russians also experimented with H2, i have one of the manual depth gauges calibrated to 300m. it would be interesting to read through some of their documents.

I think I remember reading a story about this…, it didn’t end well.

Reminds me of "lets build a deep sea exploration vessel out of carbon fiber, ignore all of the warnings and safety precautions, and immediately goto the Titanic!"

Ignoring problems and calling that ignoring them is progress ... but ay, making the inherent risk sexy looking is one way of getting support.

Very interesting. Thank you for sharing and feedback. For my part, during my dive at -312m in Font Estramar cave, with a trimix 4/86 :
I only felt very weak HPNS. Exercises allowed me to check my lucidity at different strategic depths.
Concerning the density of the gas breathed of 8.56 g/l ( -75,60m air equivalent ), the Joki being a very flexible rebreather, I did not feel any discomfort at -312m. Regards Xavier Méniscus

Wow this was fascinating!

This was an amazing slide and documentary!!! Thank you for sharing!

A glimpse into a world that might as well be another dimension. I understand the science, but I am so claustrophobic that the mere thought of being underground makes me unwell. I respect the folks that can do it, but it seems purely for sport though.

It's mind boggling how advance these guys are

When its goes Boom. Aussie Aussie Aussie Oi Oi Oi

Show the screen, not the speaker. Duh.

Truly a difficult task to solve. Would prefer building a micro submarine versus this method. The substantial volume of tanks needed plus issues with hydrogen & extreme temperature is beyond simply challenging a diver.

Great talk. Thank you.

Richard Harris has a video on his channel on going to depth of 245m

really interesting talk!

Who funded this work ?

But what about hunger and human waste disposal? How did you manage?

Why not use helium?

Kudos for pushing the boundaries and advancing diving. Fascinating talk!

Who mixed the hydrogen and how? Why didn't RH switch to Hydrogen mix at 150?

At the end of the Younger Dryas, Sea levels rose over 400 ft. On our deepest dive, we can barely see what was the shoreline before the Younger Dryas.

'we dealt with the problems by ignoring them'

True beacon of safety right here

Neat!

If you are going to mix hydrogen and oxygen in a plastic bag always put the oxygen in first. Don't ask me how I know that....

Why didn't you just test the flammability of the 3-67-30 hydreliox mix? A bag of straight H2 being flammable doesn't provide any useful information.

Impressive.

Fascinating!!

Now I'm really curious how different it would be to be on Deuterium instead of Hydrogen.

Keep at that science guys, as rebreather diver this is awesome

Looks like our exploration of the water filled caves below the Earth may be making leaps and bounds . Guess this will also have a float on effect to commercial deep saturation diving. Interesting times ahead indeed.

Brilliant!

Disappointed that the slides were not fully visible throughout the video

The production team Finally switched to PIP right as I was about to exit 🤣👍🏾

Never underestimate the willingness of the greedy to throw you under the bus.

I can't believe this is the eighth time I'm smashing open my piggy bank on the same day!

The Tsunami wave crashed against the raised houses and broke the pilings as if they were toothpicks.

When we quit thinking primarily about ourselves and our own self-preservation, we undergo a truly heroic transformation of consciousness.

First of all, this is amazing diving and I'm really grateful for you sharing your knowledge Dr Mitchell, and the team overall sharing their incredible adventures with us all.

I know that having a wildly incorrect PPO2 in the loop is bad for plenty of other reasons, and these are really weird dives anyway for example closed curcuit bailout, extreme decompression requirement etc.

But you have to admit there is just something terrifying about oxygen and hydrogen together in a compressed cylinder. Also, consider what could happen if the PPO2 increases in the loop beyond the lower flammability limit. We know already from oxygen incidents that small flakes of chrome or other contaminants being thrown through valves and first stage regulators can function as an ignition source, I just shudder at the possibility.

Just off the top of my head, the introduction of H2 creates a whole class of new hazards that no one has any experience managing:
- The loop that isn't being breathed can still cause problems if it's PPO2 isn't managed correctly.
- PPO2 mismanagement by a buddy could cause problems for you
- A blending error could result in an explosion much more energetic than simple overfilling

Good luck to you guys, but I'm glad I'm not the one taking these first steps.

"we largely resolved these concerns by ignoring them" 😎love it

I love it, a comprehensive testing programme, brilliant. 🤣🤣

i just hope to see self resetting scrubber one day ;)

Oxygen in the atmosphere is approximately 21%. Given that what they were breathing was 3%, yes it may have been flammable, but not ''explosive''.

just send down a robot....this is ridiculous....sorry just free speech happening

The device might work, but I find it extremely dangerous : hydrogen is explosive (any mix ratio between 3% to 60% hydrogen with air explodes), as anyone with basic bio-chemistry understanding would know, the human body is full of catalists to allow the chemical reactions needed to live. What I want to say is that in my opinion, breathing hydrogen threatens you of lung fire, with 3500°C flames, I will never try that

Amazing presentation. When is N = 2 happening?

So they are going to try and go deeper eventually?

The level of stupid in all this is mind boggling. Breathing a mix of oxygen and hydrogen, under pressure, in a cave, under water. 🤯

Let’s go diving… in a cave… in 6c water… to a depth of 300m… oh and we might explode. 😂

Surprisingly negative posts in the thread. Experimental is experimental but there is a history of hydro hydreliox diving 500 to 700 metres. According to our friend wiki this is the 54th such experiment. With COMEX having simulated 701 metres my only question is.... When do you plan to go deeper?