"Build Your Own Diving Lung", Revisited in 2018 -2022

[antique diver]

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The following paragraph by ScubaLawyer came from a different thread, but I am re-posting it here since it is relevant to DIY diving equipment and the adventurous early Scuba divers that would go to great lengths and dangers to get underwater. This is Mark's response to my request to hear more about his Father's diving during WWII. Thank You for the story and great photo Mark!

Dad always talked about snaking the emergency O2 tanks from the cockpit of his B-24 (not the huge O2 tanks that lined the walls aft of the cockpit and forward of the bombay doors/Norden Bombsight). He talked endlessly about spearfishing the shallow reefs of Waikiki, the walls off Kahuku, and the reefs off Barking Sand Kauai when he was stationed there during WWII. I never thought to ask him what he used for a regulator, if anything. I have a faint recollection of him saying something about using his oxygen mask from the plane and breathing O2 that way. I can only assume he would open the valve, take a hit, and close the valve again - letting exhaust escape around the face seal. That is only my wild speculative guess as I really have no clue. He passed in 2012 at age 90 and all of his Army Air Corps crew are dead as well. Shoulda, woulda, coulda, but didn't.

1944 Muroc Air Field - Dad kneeling 2nd from left.jpg

M

1944 Muroc Air Field - Dad kneeling 2nd from left.jpg

[rhwestfall]

Bill, think you have a very valuable regulator:

https://www.ebay.com/i/123830452109?_tr ... noapp=true

[antique diver]

Bill, thing you have a very valuable regulator:

https://www.ebay.com/i/123830452109?_tr ... noapp=true

I wish

I think they put the decimal in the wrong place!

[swimjim]

quote from Gone With the Wind "Askin ain't gettin' "

[antique diver]

I finally got around to trying some new modifications to the Diving Lung in an attempt to improve the performance at depth. As the comfortable diving season wound down last year I was pleased with the very easy inhalation effort as long as I kept the breathing rate slow and easy. The reg just wouldn't deliver enough volume to allow for breathing under any conditions other than easy relaxing dives.

I thought about trying a front mount to generally put the demand valve in a higher pressure than my lungs, but never gave it a try other than momentarily holding the whole tank and reg in front of me in a pool dive. So yesterday morning I put together a simple trial harness that held the regulator body comfortably against my upper chest, just below the collar bone line. Ran a longer HP hose from the back mounted tank, and the whole rig felt pretty comfy, so I called up old vintage diver Milton and headed to the lake with several other items to also try out.

I failed to get any photos of my chest mount, since M hadn't been diving (other than a few minutes with me in a pool last year) since the early -70's, and I didn't want to overload him with a camera. I call him a vintage diver because he did learn on a double hose reg in 1970 with no BC or inflatable vest.
Good news is that even though I outfitted him with a modern rig including back mount BC, he never needed to adjust his buoyancy with air in the BC. He properly weighted and controlled his buoyancy with his lungs... imagine that. He looked and handled himself as if he had never been away from diving for so long. Great... now I finally have a local vintage diving buddy!

OK, back to the "Lung". The front mount was comfortable in the water, but since the cracking effort was already very low the Lung dribbled air pretty much constantly and delivered positive pressure unless I turned on my back, and in that position it was fine. So that was a disappointing but not totally unexpected result, and I'll just go back to the conventional configuration with the Lung between my shoulder blades. Still a pleasure to dive with like that, but just can't exert a lot of effort and gotta stay out of deep water.

Next I may try bringing a little higher intermediate pressure to the demand valve than the existing first stage will allow. I'll have to use a small simple piston first stage at the tank valve with hose bypassing the Bendix first stage, and going direct to the second stage. Problem is it will require drilling and tapping an access port, and I'm not yet sure where or even if I will do that yet.

[Vancetp]

I'd like to offer this comment with the utmost respect and congratulations for what you've accomplished with this project. I love what you have done, and you (and your wife!) have done it very well. The workmanship and attention to detail are awesome and the rig is a tribute to the early divers who made and dove these.

While I totally understand the wish to improve the performance of this conversion by hook or crook, it seems that you have already accomplished the goal in spades. I think you've probably gotten pretty much the most out of the limited potential of the Bendix regulator. This is what diving was like in the first years. You might make some small performance gains by raising the IP or improving exhaust valve position, etc., but you did it! You have reproduced the rig that worked to get an average human breathing underwater at a depth of 30 fow!

Adding a remote first stage to overcome the limitations of the original seems to me to be overkill. and to be contrary to the original idea which was to make the oxygen diluter into a scuba regulator. Sure, a ScubaStar first stage piped into the demand regulator might improve performance, but that wasn't an option to the pioneers making this conversion.

This rig is something to take out for a fun vintage dive, or to the local dive shop training pool to let the scuba students try out, just to see what the early days were like! I don't think it would be a wise choice for a 130fow dive to repair a pipeline?

[antique diver]

You're right Phillip! I appreciate your last post. I totally agree with your comments, and was actually wishing that I had not even made that last statement about trying a work-around improvement. That would pollute the simplicity of the Diving Lung.

In the Lung's current configuration it's pretty much like what could have been home-brewed in the 40's and early 50's by dreamers wanting to go underwater so badly that they were willing to take the risks involved.

And that was my original goal. It's not safe for a beginning diver - it could quit working. (I'll always remember old John Coffee's story about one of them blowing apart... See early pages of this thread.) Heck, it's not even safe for an experienced diver if he did not understand and respect its limitations, and was not prepared to deal with a worst-case scenario.

Being underwater with my home built Bendix Diving Lung is a blast, and it gives me a real feel of what those early adventurers experienced. I love it!

Tucker's Diving Lung.JPG

[Vancetp]

Thanks for showing us your build of the Bendix oxygen diluter conversion. This was an important part of the history of scuba diving, and your authentic recreation of the system is an amazing feat. I followed with great interest (and some relief that now I don't need to do it!). Keep us posted on subsequent dives with this setup!

[Vancetp]

Hi, Bill.

Are you using a DSV on the Bendix? I thought I saw one on your reg back a few pages. I have been fooling around with Titan II and Dacor 4/800 Balanced DH conversions, and found that the DSV can throttle back the amount of air of a regulator supplies. In the case of a rig with a strong venturi, or in particular, an over-strong venturi, this is a good thing, and prevents air from blowing past the mouthpiece into the exhaust hose.

I'm not dissing the DSV! I love them, and always use one when I dive a double hose regulator. But, if you haven't, try the Bendix with a regular USD hoseloop. I almost suggested the Nemrod mp you had on in the beginning, but they're a bit more restrictive than the USD.

Just a thought.... I'm guessing you'll get easier breathing and a feeling of more available air.

[Vancetp]

I got a great deal on a super clean Bendix oxygen diluter. CRAP!!! I really wasn't going to do this..... Maybe I'll be satisfied with just looking at how it works.

[antique diver]

Hi, Bill.

Are you using a DSV on the Bendix? I thought I saw one on your reg back a few pages. I have been fooling around with Titan II and Dacor 4/800 Balanced DH conversions, and found that the DSV can throttle back the amount of air of a regulator supplies. In the case of a rig with a strong venturi, or in particular, an over-strong venturi, this is a good thing, and prevents air from blowing past the mouthpiece into the exhaust hose.

I'm not dissing the DSV! I love them, and always use one when I dive a double hose regulator. But, if you haven't, try the Bendix with a regular USD hoseloop. I almost suggested the Nemrod mp you had on in the beginning, but they're a bit more restrictive than the USD.

Just a thought.... I'm guessing you'll get easier breathing and a feeling of more available air.

I just used the DSV on one of the first pool tests because I had that hose loop assembled and handy. I liked the looks of the Nemrod, but settled on the Aqualung hoses and straight mouthpiece with valves for the better flow characteristics. Been diving it that way in all the open water use and it is comfortable. I'm thinking of making something out of a copper pipe tee to be more period/home-built correct, but I'll want to make something for mouthpiece valves to help keep the inside of reg dry (and inside of me dry too).

The DSV is going on my hot rod modified Trieste to keep some of the air flow controlled from going out the exhaust due to much improved venturi. Haven't even tried that combo yet, but it is definitely needed, and I'll get around to diving it soon.

[antique diver]

I got a great deal on a super clean Bendix oxygen diluter. CRAP!!! I really wasn't going to do this..... Maybe I'll be satisfied with just looking at how it works.

Keep us informed!

[ScubaLawyer]

The DSV is going on my hot rod modified Trieste to keep some of the air flow controlled from going out the exhaust due to much improved venturi.

Ok, I'm intrigued!

[simonbeans]

Trying not to be the wet blanket on this thread, but the discussion of DSV on this forum section is beyond the scope of Classic Vintage Diving. The OP discussion on the Bendix is fine, but addition of DSVs (might be the new one for the Argonaut?) is NOT. You could discuss the DSV's use on other forum sections.

[Vancetp]

So let's move over to the modern DH section and hear about this hotrod Trieste!