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Post by SeaRat on Jul 16, 2024 16:15:04 GMT -8
Hello Vance Found in your fotoscream that you did a lot of work with DIY duckbills in the horn . Have you tested whether the duckbills restricted the airflow of the auxilary exhause valve ? For testing : Close the horn opening by removing the inhale valve in the mouthpiece or fix inhale valve in position open . Now exhale as quick and as much as you can . The only way out for the exhale now is the auxilary exhause valve . There should be no great difference in exhale resistance with duckbill or without duckbill in the horn . Obviously nothing in the horn is best for safety . Very good idea to use excess rubber from a duckbill for replace an old rubberband . Greetings Rainer Rainer, This is the first documented case I've heard of where a double hose test breath could cause a lung overpressure. The exhaust needs to be blocked, or offer so much resistance that it could not exhaust the air. This can happen if the mouthpiece mushroom nonreturn valve is stuck, and the exhaust is really poor. I'd highly recommend that a diver test breath the regulator for exhaust before attaching it to a tank. I've have one of my Healthways Scuba Delux exhaust stick that way (mouthpiece), so this is good information to have. But, it applies to any single stage double hose regulator too (Mistral, Healthways Scuba Gold Label, etc.). John
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Post by vance on Jul 16, 2024 18:33:23 GMT -8
Why did the first version of the Scuba not have an additional exhalation valve ? I'm pretty sure that they started drilling auxiliary holes when they started installing duckbills. The early versions did not have either.
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cg43
Pro Diver
Posts: 117
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Post by cg43 on Jul 17, 2024 3:18:32 GMT -8
Hello John
Yes , the duckbill can be build in the way that it can not interfere the holes in the horn . In CG45 Healhway Scuba is a picture where it looks like build exact this good way .
The fatal accident that I have briefly described happened with a single hose reg. and can right this way only happen with a two stage reg.
In the case the first (and only) stage freeflowed , the closure of the exhaust on the Suba without auxilary exhaust is constructively caused.
The exhaust diaphragm/horn valve has the task of preventing blowing off when the exhalation opening to the water is higher than the center of the inhalation membrane. The advantage of this design is that the exhaust valve can be placed far away from the center of the inhalation membrane, for example to circumvent the Cousteau/Gagnan patent. During normal exhalation, the exhalation pressure cannot enter the can because of the inhale valve in the mouthpiece. It therefore only acts on the horn side of the exhaust diaphragm , the exhaust opend .
In the case of a freeflow, the freeflow pressure acts on the entire inner surface of the exhale membrane. Although this pressure is also piped to the horn side, its area is smaller. If the water pressure is now lower than the freeflow pressure, and this is always the case in a normal swimming position, the horn is securely closed. You don't even need a huge blast for that.
Greetings Rainer
Edit : The closure of the exhaust on the Suba without auxilary exhaust is not a malfunction but purely constructively caused.
This can be misunderstood . Hence the change to:
In the case the first (and only) stage freeflowed , the closure of the exhaust on the Suba without auxilary exhaust is constructively caused.
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cg43
Pro Diver
Posts: 117
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Post by cg43 on Jul 17, 2024 5:02:19 GMT -8
Hello vance
The holes with the outer rubberband and the duckbill have two different funtions . There was a reason for the duckbill even it ist not absolute nessesary .
The auxilary exhause valve is an absolute safety necessity . Healthways should be grateful to god if there has not been a case where they have been sued for their first version.
Greetings Rainer
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Post by SeaRat on Jul 17, 2024 9:32:22 GMT -8
Hello vance The holes with the outer rubberband and the duckbill have two different funtions . There was a reason for the duckbill even it ist not absolute nessesary . The auxilary exhause valve is an absolute safety necessity . Healthways should be grateful to god if there has not been a case where they have been sued for their first version. Greetings Rainer Healthways had a very good mouthpiece on the first Scuba regulator, the Hope-Page mouthpiece. It had the most advanced non-return valves in the business. In written documentation I have seen somewhere, they were worried that over time and storage the exhaust diaphragm could become fixed to the exhaust tube, and so they drilled the auxillary exhaust holes. Saying that, I had a Hope-Page mouthpiece non-return stick this spring. The one time I had experienced the complete exhaust blockage was with the Scuba Deluxe regulator, without a non-return in the mouthpiece. When I exhaled, the main diaphragm ballooned and covered the exhaust mushroom on the case. That was fixed in the Healthways Gold Label case, where they put a metal piece next to the exhaust mushroom to keep the diaphragm from covering the exhaust, and blocking it. But I had to abandon a dive because of that problem, get a different regulator, and then continue the dive. John
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Post by vance on Jul 17, 2024 11:16:31 GMT -8
HW installed the L piece on later Deluxes, somewhere around serial # B8500. That is very late, so there are a lot of Deluxes out there with this potential problem. The fix might have come about when they were designing the GL model.
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Post by vance on Jul 17, 2024 17:15:58 GMT -8
BTW, a few years back, JB posted how he JBWelded (heh!) an L piece onto his Deluxe to solve this problem. I don't remember in which thread his post appears, but it's pretty easy. All you need to do is rough up the contact area a bit, mix up the epoxy, and clamp or weight it in place.
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Post by SeaRat on Jul 17, 2024 17:31:28 GMT -8
BTW, a few years back, JB posted how he JBWelded (heh!) an L piece onto his Deluxe to solve this problem. I don't remember in which thread his post appears, but it's pretty easy. All you need to do is rough up the contact area a bit, mix up the epoxy, and clamp or weight it in place. I did something similar, as I glued in a large stainless steel nut where that "L" piece should be. All it takes is something to hold the diaphragm off the mushroom enough that air can move through. On another note, I just looked at the two Healthways Scuba units I got off E-Bay a while back, one of which has not been dived by me. The one I haven't dived has no holes in the exhaust tube for the auxillary exhaust. The other has the holes, but the rubber band had dissintegrated and was removed. Both are now in parts on my workbench. John
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Post by vance on Jul 17, 2024 17:42:23 GMT -8
As I said before, the disintegrated auxiliary rubber exhaust band can be replaced with a piece of silicone duckbill material. If you need some, I have extra, and would be happy to send you a piece.
The no-holes regulator can be dived safely if there's no duckbill and it's equipped with the James/VTP exhaust diaphragm kit.
If you need one or two of the kits, please let me know.
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cg43
Pro Diver
Posts: 117
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Post by cg43 on Jul 24, 2024 9:52:07 GMT -8
Hello vance
You write :
In the case of a freeflow the exhaust is closed by the exhale diaphragm . It does not matter if there is a duckbill in the horn or not . If anyone has an old no-holes SCUBA he can easy test this . Fix a ballon over the mouthpiece , thats your lung . Now push down the main diapragm with some tool through the slits , that simulate a freeflow . Good luck for your lung ! Please tell us your result !
Greetings Rainer
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Post by vance on Jul 24, 2024 13:19:06 GMT -8
There you have it! Don't dive a Scuba w/o an auxiliary exhaust.
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Post by vance on Jul 24, 2024 17:08:58 GMT -8
It's unlikely you will encounter a Scuba without the auxiliary holes and band. I have had several, but I've had a lot of Scubas! Most have the drillings.
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Post by spirou on Aug 8, 2024 11:17:55 GMT -8
IMG_20240808_170846_714 by Patrick Michel, sur Flickr IMG_20240808_203611_601 by Patrick Michel, sur Flickr Two box form the US arrive today, 😙💨 😃 one from Phil, with special pièces, from him, and James, the second is a little SCUBA,(from ebay) with dust , and dead bugs inside, (as I can see inside through the pipe). The rest of the hoses are bleu. There is also a rest of duck bill . Last weekend I test a BCD, and a FENZY X4, with a DH, the DH regulator must be as close as possible of the lung, so a I buy a transpac, with a rec wing. I just keep the harness and the wing. I haven't feel difference, compare with just the transpac harness set on the tank, breath as I feel were the same, (or very closed) with and without the wing. FENZY X4, is compact, and not much present for a horse collard, my weight belt was good, unnecessary to put much air in the FENZY when a was at 60 feet. The FENZY were not so confortable then the transpac, but lighter, and safe, in case of problem your head will stay out of the water. It is the difference between BDC and live vest. I will post photos in another thread this weekend. Respectfully Fred
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