How is scrubber exhaustion measured?

[The Chairman]

I did read his posts and tried to say this diplomatically above. Thanks for phrasing it in diver-ese

Not you... I want the OP to read YOUR posts over and over again!!! You were spot on!

PS: I edited that post for clarity!

 

[Wibble]

In theory, building a rebreather's really easy. Just need to circulate your breath through a suitable absorbent (scrubber) such as Sofnolime.

In practice, whilst the basics are easy, keeping a human alive is hard as they're so darn fragile.

Scrubber usage is difficult to measure and depends on many variables; temperature, pressure, throughput, scrubber size and configuration, lungs, angle ... a long list. Then there's the challenge of making it easy to breathe -- the "work of breathing" -- as that affects how well the human works.

The first rebreathers were developed around WW2, using pure oxygen. It's taken many decades for the additional technology to evolve to where we are today; you simply rock up to a Rebreather training course armed with $10k and you've a good chance of living a long diving career.

It might be worth looking up the "rebreather CE certification process"

Some interesting material here: RESA - The Rebreather Education & Safety Association

 

[Akimbo]

As a school project, you might consider making a transparent vertically mounted cannister and use an absorbent that changes color as it is exhausted. I believe that Barium hydroxide is still sold that turns purple when converted by CO2.

Are you building a pure Oxygen rebreather or mixed gas? You must be very careful to completely purge the loop of air (Nitrogen) with O2 rebreathers, even if it is just used on a table-top demo. You can easily consume all the Oxygen in the loop and not notice the need to add Oxygen, causing hypoxia.

The first rebreathers were developed around WW2, using pure oxygen.

Actually, over 90 years before that. They were first used in mine safety but were quickly adapted for divers.

 

[super scrubber]

Nice! I'm sure you'll hear this multiple times and at the risk of stating the obvious: it's a big jump from building one for a school project to actually diving one, especially a home-built. You'd need open-water diving certification and some diving experience before taking a CCR class, and a lot of diving and engineering know-how and experience to build one that is safe to dive.

Best regards,
DDM

My final is diving in a homemade one for 1 hour in my DIY one so I'm SOL if I don't dive in it. I'm trying to get as much info as I can so I can build in a mega factor of safety.

 

[Marie13]

My final is diving in a homemade one for 1 hour in my DIY one so I'm SOL if I don't dive in it. I'm trying to get as much info as I can so I can build in a mega factor of safety.

You apparently don’t even have an open water cert. What possessed you to take up this project? Your final could be your final. I’m in the midst of CCR training now. It’s no joke.

 

[Brett Hatch]

My final is diving in a homemade one for 1 hour in my DIY one so I'm SOL if I don't dive in it. I'm trying to get as much info as I can so I can build in a mega factor of safety.

This is really dangerous, and you would be a fool to try it. I'd strongly recommend picking a different project, or to at the very least modify this project such that nobody needs to actually dive the rebreather. F*** around here and there's a good chance you will find out.

[edit to add: on re-reading this thread, this guy has got to be a troll. If you are a troll, congratulations, ha ha, you got me. If you are not a troll, take the advice in this thread and abandon this idea]

 

[The Chairman]

My final is diving in a homemade one for 1 hour in my DIY one so I'm SOL if I don't dive in it. I'm trying to get as much info as I can so I can build in a mega factor of safety.

Please rethink your goal. On the advice of many of your advisors (us), you've come to the conclusion that you should do a simulated dive instead. Use an ESP 32 set up to measure O₂ and CO₂ before and after the scrubber. Create a breathing mechanism and add CO₂ to the mix while bleeding some off.

This project is not worth your life. I know at least a dozen people that have died on tested rebreathers. No, not "know of", but I considered them actual friends and dove with at least half of them. One was set to teach me about rebreathers and died on his a few days before the class. Some OW divers refer to them as "little boxes of death". Death on a rebreather is completely painless with absolutely no advance warning you're going to die. It's my opinion that one of those deaths was a suicide because of this. He had advanced cancer and was in constant pain.

 

[broncobowsher]

School project, cool.
Total lack of experience, not cool.
Here is some real world education that isn't often taught that well in schools. Go find someone that has some experience. To an extent, you are doing that here. But I mean a real human being. I don't know that part of the country for instructors so I am not throwing any names out. Hopefully someone here would know a local who would spend an evening with a (any brand, or a few different brands even better) rebreather and just get to know what you are actually going to be working with. There is stuff you learn by being around people that just can't be learned by reading text. Real life experience.

 

[Sevenrider860]

Alex Peirce on "Build your own rebreather".

 

[azstinger11]

Hey mods can we move this accidents and near misses, or do we wait tell the final is due lol?