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Post by vance on Nov 27, 2020 15:51:54 GMT -8
This pic shows the overpressure relief valve in the first stage, and the second stage/diaphragm lever. The diaphragm has a plate in the top with a hole for the threaded arm that is shown on the end of the lever. A pair of nuts adjust the diaphragm height, unlike (most?) scuba regs which adjust the lever height. The second stage is remarkably like the second stages we're used to seeing on scuba regs. The soft seat disk is a direct replacement for USD seats.
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Post by nikeajax on Nov 27, 2020 15:56:17 GMT -8
John, I feel pretty safe in saying that this is more a mental exercise for PY than anything else: he and I are a lot alike that way. The main idea is pushing the original idea that early divers had, but to make it actually safe... JB
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Post by nikeajax on Nov 27, 2020 15:57:34 GMT -8
PY, thanks for sharing your ideas with us: it's very enlightening!
JB
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Post by vance on Nov 27, 2020 16:08:53 GMT -8
I just lightened the exposure on the picture a few posts up so it can be seen more clearly. The radiator looking thingy JB is talking about is the cockpit air inlet (mixer) which allows air to be mixed with the oxygen coming out of the second stage. There's a configuration of brass bits that run from the intake horn to the second stage opening that do the mixing that have been removed and will not be used in the conversion. The cage with a spring inside the mixer box is a clapper valve. (Oddly, it looks just like the ones used as non-returns in Soviet mouthpieces.) That will go, as well. The domed cover has been cut off, mixer components are removed, and the top of the fitting has been machined flat, simply to use the fitting as a plug for the mixer mounting hole. The hole will be sealed with a smaller threaded plug which might double as a mounting point for the exhaust valve assembly, if I don't fit it inside a top box. The PopSci version used this hole for exhaust gases, but it is not a good design as I described above.
I know, it looks like I'm working on this. Phil, I think part of the problem is that this "regulator" was not designed as a demand valve, but rather as a continuous feed valve to mix outside air with oxygen from the cylinder so pilots could function above 10,000 feet altitude. It was also meant to be used with a half-face mask (covering the mouth and nose), with continuous feed rather than demand feed. As such, in trying to convert it to a scuba demand system, the entire unit has to be redesigned in order to give the diver the required amount of air, at a breathing resistance that allows the diver to physiologically function. Because of these limitations, it has been recognized as a potentially hazardous modification (as you've recognized by noting that people have died trying to actually use this modification). So while this is an interesting intelectual exercise, please keep in mind the extreme limitations of this redesign and ensure your safety in any actual tests. John Actually, no. It is a demand regulator. It has 2 stages, and it was not generally meant to be used as a continuous feed device. There IS a knob on the HP inlet that will allow continuous feed, but with the valve in the closed position, the regulator works as a demand unit. There are both 2 stage and second stage diluters. The one I'm converting is a 2 stage. LP diluters would need a remote first stage. You are correct about the severe limitations of this conversion. It is not a viable unit for general use (although PopSci touted it as such!!). I am only interested in it as an historical recreation of a very important step in the development of scuba diving as a sport. I think that I can make it work better than the PopSci design, and keep its 1950s integrity intact. But, improvements might be minimal, and the notion that I can do better, hubris. This reg isn't going diving in Monterey.
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Post by nikeajax on Nov 27, 2020 17:53:53 GMT -8
PY, what if you just put a Feenicks (Phoenix) nozzle on it, it'll breath much better that way... Sorry, I just couldn't resist Keep on tuckin', buuuddy!
JB
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Post by vance on Nov 27, 2020 18:46:00 GMT -8
The temptation is to make improvements to a device that weren't possible back in the day. I once hotrodded an IBM PC by installing a Pentium chip powered motherboard, 8 MB RAM, huge hard disk (probably 250mb!), and all the trimmin's, into an original PC or XT case. It was a screamin' XT. All said and done, I had a Pentium PC.
Then, there was the '55 Chev with a 350/350, and the other '55 Chev with the HP 348/Muncie, and the '65 VW bug with the 912 Porshe engine, and all the rest .....
But, they were kew!
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Post by SeaRat on Nov 28, 2020 11:54:37 GMT -8
I just found this website on the CG-45.com site. www.cg-45.com/regulators/Homemade/It talks about what you are thinking about too, and has a separate article from Popular Mechanics in January, 1955. It also cited this article The Journal of Diving History Spring 2011, Volume 19, Issue 2, Number 67 - Ed LaRochele John
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Post by vance on Nov 28, 2020 16:03:35 GMT -8
If you go to the CG-45 site and look under S for Seahorse, there are 4-5 examples of the commercially offered conversion. BTW, it seems that a company called Sea-Net previously offered a conversion, the SeaBreather SD-5, in 1952! I'd like to see one of those.
An interesting feature of the Seahorse regulator is the rectangular block mounted on the inlet valve with a rod affixed to it. It would suggest a reserve valve, but it is not a reserve. It operates the constant flow valve. The block replaces the normal red knob, and is operated similarly to the reserve pull rod. You would have had to be a contortionist to reach the red knob, so this was a mod that allowed the diver access to this valve. When overbreathing the regulator, and desperate for air, (s)he could pull the panic rod which would push a constant high flow of air to the mouthpiece.
As I've said before, "Yikes!"
The PopMech article is interesting b/c it utilizes a chest mounted, converted second stage pressure valve (I can't see what kind of valve it is from the text, but it doesn't appear to be a diluter), which is fed IP air from a remote first stage via a hose. The first stage PM recommends is an interesting R.A.F. part which is a combined first stage/tank valve.
Huh. I know there are US second stage diluters, but I've never seen the first stage that supplied them.
Anyone?
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Post by nikeajax on Nov 28, 2020 16:33:07 GMT -8
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Post by SeaRat on Nov 28, 2020 16:34:08 GMT -8
Practical Mechanics is a British publication. Perhaps David Richie Wilson could find it. What do you think, DRW? It's the January, 1955 issue.
John
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Post by vance on Aug 31, 2021 16:22:11 GMT -8
I'm doing some more work on the oxy diluter to dh regulator mod. Bill T has inspired me by making some improvements to his working setup. He has successfully increased the airflow, possibly by increasing IP. However, he ran into a problem b/c what we believe is the IP adjuster has been so aggressively staked (to prevent unwanted turning), that he is unable to turn the adjuster without fear of damaging irreplaceable parts. Since his is a working regulator, and I'm not there yet, I decided to set up my diluter body on the mill to see if I could remediate the staking punch. I used a small ball bit and drilled down into the stake. It was successful, and I can now turn the plug. I also made a tube that directs air from the second stage directly into the intake hose. Without the mixer in place, second stage sends its air out into the case which is very inefficient for Scuba. The director tube has 3 steps to fit the diluter's 3 different sized bores. The air passage bore is 3/16". It might get opened up or reduced with a jet later, depending.
The tube fits into the second stage opening (looks like a bullseye) and I put an o-ring at the bottom to seal it so no air leaks into the box. The tube sits a little proud of the horn end, so that the tube compresses the o-ring when the airhorn ring is tightened down. This photo shows the tube in place, and secured by the airhorn.
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Post by nikeajax on Aug 31, 2021 16:42:44 GMT -8
Again, very inspiring sir! JB
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Post by antique diver on Aug 31, 2021 19:07:09 GMT -8
The Bendix that Phil has actually is a demand regulator, with the option of completely bypassing the 1st and demand stages by simply opening a conveniently placed (in the aircraft usage) valve knob. In diving configuration it can be drastically difficult to reach. The whole point of the "diluter" function is to conserve the limited Oxygen supply by mixing it with air in proportions appropriate to the altitude. The demand function is the normal mode of operation for the same conservation of gas.
I did a conversion on the same model in 2018 (and still tinkering and shallow-diving with it), and can say with conviction that following the Popular Science "how-to" would result in an extremely dangerous underwater breathing apparatus! There is a much better way... not saying it's safe, just safer than PS version.
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Post by vance on Sept 1, 2021 7:40:31 GMT -8
Aside from the limitations of the regulator's performance, these units suffered terribly from salt water exposure. The aluminum body and internal parts corroded badly, like the early DivAirs and other bronze or aluminum regs. These diluters were not meant for underwater use. The PopSci conversion was a very quick and dirty setup, and the article woefully inadequate on details. The fabric demand diaphragm was coated with rubber cement, and only a few parts were added/removed. And the hoseloop was not well designed, esp. the exhaust side. Note that both the intake and exhaust hoses go into the diluter box on one fitting. This mixes fresh air with exhaust air inside the box which will lead to too much CO2 going to the diver. Exhaled air will cause condensation to form inside, and any water in the exhaust hose will also enter the box. Exhaust air should be routed outside the box, either by use of an external fitting with an integral one-way valve of some sort, or an exhaust cover (like my Costco chicken can) with an internal one-way valve.
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Post by vance on Sept 1, 2021 7:58:08 GMT -8
AntiqueDiver chronicles his diluter conversion in a very interesting thread on VDH. His conversion goes deeper into modification than the PopSci conversion, including a homemade silicone diaphragm.
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