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Post by SeaRat on May 28, 2011 21:09:46 GMT -8
I have also checked out the US Divers Company original BroXton, the Aqualung regulator. The BroXton Coalition would be happy to note the results of this water test: Again, as with the DX Overpressure Breathing regulator, no backup of the water. This means that the water can get out as fast as it goes in. The duckbill valve on these original USD regulators was very efficient for the exhaust. Improvements came over the years with the inhalation resistance. John PS--be sure to go back to the first page, as I have two more posts there from today, one on the Dacor Dial-a-Breath and one on the Sportsways Hydro-Twin.
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Post by duckbill on May 29, 2011 15:52:10 GMT -8
Of all the regulators I have looked at, this (Dacor Dial-A-Breath) has the most backup for water flow through the system...........If you look at the graph, it shows the resistance for the exhalation pretty well, with the "Competitive Regulator" most likely being the USD Aquamaster. When I look at the graphs I see that the Dacor (Fig.4) had the edge over the Mistral (Fig.2) at recreational depths by one to two centimeters of water of exhalation resistance. Also, the Mistral with the non-removable exhaust housing (Fig.2) likely had the duckbill inverted in the horn just exactly the same as a DA AquaMaster. If so, the the DA AquaMaster's exhaust data would be identical to the Mistral's, and could not be the "Competetive Regulator" in the Dacor graph (Fig.4). No?
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Post by Captain on May 29, 2011 16:37:05 GMT -8
On the regulators with the removable exhaust tube the duckbill did not pass through the tube. It was slipped over the sub end of the tube inside the can, glued with Pliobond cement and tied with string. This is still the way I do it when I rebuild one. That way it doesn't reduce the inside diameter of the tube. You can use a current type duckbill by cutting it to the correct length.
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Post by SeaRat on May 29, 2011 18:08:49 GMT -8
Of all the regulators I have looked at, this (Dacor Dial-A-Breath) has the most backup for water flow through the system...........If you look at the graph, it shows the resistance for the exhalation pretty well, with the "Competitive Regulator" most likely being the USD Aquamaster. When I look at the graphs I see that the Dacor (Fig.4) had the edge over the Mistral (Fig.2) at recreational depths by one to two centimeters of water of exhalation resistance. Also, the Mistral with the non-removable exhaust housing (Fig.2) likely had the duckbill inverted in the horn just exactly the same as a DA AquaMaster. If so, the the DA AquaMaster's exhaust data would be identical to the Mistral's, and could not be the "Competetive Regulator" in the Dacor graph (Fig.4). No? Duckbill, A couple of things--yes, the Dacor Dial-a-Breath was close at the surface to the duckbill of the time (1959). But at depth of over 60 feet, and under higher breathing rates, it was not comparable. Also, the duckbills used were the ones available in 1959. They have progressed since then. If you'll look at the below description and photo from the US Navy Dive Manual, 1970 (page 347; these were the 1950s duckbills, as they did not update the photo to the 1960s or 1970s), you'll see that the duckbills of the time were different than the ones of the latter part of the 1960s (which is what is available today). Even so, the duckbills were better than the mushroom valves of the time. Here's another chart from the same 1959 report which confirms that the surface breathing of the Dacor Dial-a-Breath exhalation was pretty good. It does deteriorate at depth (like all regulators do). Today, I had the Dacor Dial-a-Breath and the USD Aqualung in the water (pool--the rivers are at flood stage here, and I'm not going to dive them). The inhalation of the Dacor Dial-a-Breath was slightly better, but the exhalation was not. It was noticeable that the exhalation was much better with the USD Aqualung. John
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Post by duckbill on May 29, 2011 20:38:34 GMT -8
Even so, the duckbills were better than the mushroom valves of the time. I'm confused. The charts seem to show the opposite. Depth(ft) -- Dacor/Mistral(exhalation resistance in cm H2O) 30-- 12 / 14 60-- 16 / 17 90-- 19 / 21 120-- 22.5 / 23.5 150-- 25 / 27 180-- 27 / 31 In each case the Dacor has the lower numbers. Lower is better, isn't it? Point taken that materials and construction of the duckbills improved since the tests.
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Post by SeaRat on May 30, 2011 20:09:12 GMT -8
Duckbill, It is confusing, as there are several charts to look at. The one you chose for the Mistral was the Figure 2 from the EDU report on the Mistral. We then were comparing it to the Figure 4 from the Dacor study. These were done close to the same time period, but not in the same grouping. The figures I was looking at were from the other figure for the Mistral, Figure 3 (I believe). So let's regroup a bit. Here is the Dacor chart: And here is the Mistral chart I was using (with the older exhaust). Finally, here is a more representative value, the same type of study on the Royal Aquamaster that was done in the 1970s. Note how the Mistral with the inhalation resistance is better than Royal Aquamaster. The Royal Aquamaster has the same exhaust valve setup as the Mistral of the same time period, so I would take the Royal Aquamaster results for the Mistral. Realize that I had seen all these studies, and this is why I was saying that the Mistral would beat the Dacor Dial-a-Breath. I think that USD re-designed the exhaust duckbill between the 1959 era and when I got into the USAF, and went through the US Navy School for Underwater Swimmers. The exhaust I saw there was almost the same as todays, as long as it is the longer untrimmed duckbill. John
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Post by duckbill on May 30, 2011 21:13:44 GMT -8
O.K. It's hard when comparing apples with oranges. I went with Fig.2 as it is representative of standard duckbill configuration, with the duckbill inverted in the horn and presenting more of a constriction than the older style shown in Fig.3 which is really only used on the older regs.
Interesting the huge difference between the older measurements and the newer ones for the same exhaust setup (Fig.2 Mistral vs. Royal AquaMaster). I wonder how that can be justified. Were the duckbills really that much improved? Or was the testing machinery that much different?
Also interesting is that two sets of exhaust data were shown for the Dial-A-Breath for dial-open vs. dial-closed. I wouldn't think the inhalation settings should affect the exhaust data, and maybe it really didn't in that perhaps both of the exhaust lines fall within acceptable deviation ranges. That's why I used the average of the two to compare to the Mistral data.
I know the point here is to compare duckbills with mushroom valves, but I have to wonder how the Dacor mouthpiece non-returns compared to the US Divers. Afterall, didn't the regulators used for the testing include their standard hose configurations? Any ideas on that?
I think your water testing method is novel and graphically demonstrates the differences. But, hey, you can't fault me for giving the mushroom valves some benefit of the doubt, especially considering my username is "duckbill"!
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Post by SeaRat on May 31, 2011 19:24:49 GMT -8
Duckbill,
A few observations:
--If you'll look above at the US Navy Dive Manual representation of duckbill and mushroom valves, the one standing up at the top is probably the "new" valve that was tested. It is meant to be inserted into the intake horn, and not placed on the removable horn of the old-style USD top box. Now, if you try that maneuver with current valves, you'll see that they do not have the restriction in the center of the valve. I think USD changed the duckbill's profile.
--The Dacor Dial-a-Breath's hose/mouthpiece system was different, and more constricted. It looked more like the original USD Aqualung hose/mouthpiece than the Kleer-EZ mouthpiece by USD. The openings for the non-return valves were also smaller, as I remember (from many, many years ago). So overall breathing performance was worse with this hose/mouthpiece system on the Dacor than the USD system.
--Last Sunday I dove both the USD Aqualung and the Dacor Dial-a-Breath with the same hose/mouthpiece system, a Hope-Page mouthpiece with Mares silicone non-return valves, and Dan's SuperFlex hoses. The difference in exhalation resistance was noticeable between the USD Aqualung and the Dacor Dial-a-Breath (the Dacor breathed harder for exhalation).
John
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drado
Pro Diver
Posts: 186
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Post by drado on Jun 18, 2011 21:20:11 GMT -8
There have been test hanging weight to check how secure it is and it has not been a problem. Luis, I believe this is the photo that you were looking for: At any rate, I finally got around to trying to replicate this experiment with a silicone duckbill from my Mistral, and a duckbill eliminator from my PRAM: Parameters of the test was a water flow rate of around 6LPM. Distance from faucet was held roughly the same using my finger as a guide. Here are the results: For the silicone duckbill: (I did not have an intact original rubber duckbill to play around with in this instance) The white stuff is plumber's tape which I use to keep the duckbill on and reduces bunching of the valve whenever I remove or replace my silicone hoses. For the DBE: In both instances, there was no note of backflow. The outflow through the DBE seemed smoother than that of the duckbill - as the water in the duckbill was directed at a sharper angle through the slits than that of the circular opening of the DBE. Although difficult to quantify, the force of the water as it changed direction in the duckbill could be felt as a slight vibration. Further testing at higher flow rates will be warranted though.
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Deleted
Deleted Member
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Post by Deleted on Jun 19, 2011 16:22:21 GMT -8
Has anyone ever cut the tip of the duckbill off? I presume the valve will still close off, and there will not be any radical turn to left or right of the flow.............
Just wondering if this has ever been done as I seem to see over the past years of comments and discussions that some things never were attempted but seemed obvious.
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Post by SeaRat on Jun 19, 2011 17:55:54 GMT -8
Drado,
(The images came through--thanks.) I appreciate your work here on the DBE. I had a feeling that it would be better than the older-style mushroom valves because it does not require a direction change for the fluid.
OldMossback,
There are a couple of things that can be done to make a regular duckbill perform even better. One would be to cut out the "V" right at the tip of the duckbill, so that this portion is open. There would still be closed edges on the end of the duckbill.
You asked about whether a duckbill has ever been completely opened up, with the material itself acting to hold the water out instead of sealed edges. Well, I just did that for my hybrid regulator, the Healthways SCUBA. It has the original box, with that exhalation system, but the third generation valve with the venturi in it. I dove it yesterday, and had previously placed the cut-down duckbill which was completely opened up in the exhalation tube. It worked well to keep water out of the exhalation hose, but not inhibit the exhalation diaphragm. The one thought I have is that in the Healthways regulator, the exhalation tube is pretty well protected from external influences, such as water current. But in the USD/Voit top box, the valve would be subjected to currents coming through the box's holes. This could cause problems if there were no material holding the duckbill together at the end.
I will also say that today I had my Mossback Mk 3 in the water, and was very happy to have been using it. I had very heavy current, other problems (I'll put that in a log entry) and was glad I wasn't testing the Healthways hybrid SCUBA regulator today. The Mk 3 performed superbly, on both inhalation and exhalation.
John
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Post by elmerfudd on Jul 4, 2011 9:22:01 GMT -8
I just did this test myself using a silicone duckbill and a DBE, plus a subjective exhalation test on them both.
What I found is that the duckbill does indeed flow significantly more water without backing up than the DBE. I could turn my bathroom faucet up all the way and the duckbill kept pace, but at about 2/3 of the maximum the DBE started to overflow.
I don't think this has anything to do with the mushroom valve vs. the duckbill valve, rather I think it is a result of the constriction where the DBE inserts inside of the exhaust horn. I can pinch the mushroom valve and pull it away from the DBE so that the valve itself should have almost no restriction on the flow, and the same overflow happens.
Next test I did was to vigorously exhale directly through the horn. With the DBE, I find more resistance, but it is a uniform type of resistance. It's pretty much always the same. With a duckbill on the other hand, the exhalation is mostly easier, but sometimes with a hard exhalation it produces a flapping, farting effect. I tried repositioning the duckbill many times in order to eliminate this, but I could not. Sometimes I could make it better, but I could not eliminate it entirely. I also compared them both to an R109 and a G250V and I think the single hoses were slightly harder to exhale through than either the duckbill or the DBE.
I should mention however, that at normal breathing rates this resistance isn't noticeable. I was really blowing air through the exhaust horn hard to try to get some idea of the relative resistance.
Three things that are definitely in the DBE's favor. 1) It's tougher. Just while doing this test and repositioning the duckbill, it developed a small hole near the exhaust inlet. 2) It's much easier to remove and replace hoses on regulators with DBE's. 3) Initial hard breathing is greatly reduced. Sometimes duckbills seem to seal to themselves and for the first few breaths can be hard to exhale through. The DBE largely eliminates this.
All in all, I think the DBE is an improvement.
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drado
Pro Diver
Posts: 186
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Post by drado on Jul 6, 2011 16:54:13 GMT -8
Interesting report. I will admit that my flow testing was hampered by limited flow rates which I measured at around 6 LPM. It is quite possible that at the higher flow rates you tested the DBE could lead to the noticed overflow. I would tend to think though that this back-up of water was not caused by the restriction, but rather that the advantage of the silicone duckbill versus the the DBE is the increased compliance of the duckbill's walls, thus acting as a capacitance vessel. Here's a shot of the constriction of the DBE: Of course, the best way to test both would be the use of a manometer Overall, though, I think the resistance differences between the silicone duckbill and the DBE aren't that much in terms of performance. I agree with your assessment that the benefits you listed are what the DBE has in favor of it.
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Post by elmerfudd on Jul 6, 2011 22:12:09 GMT -8
When I did that test, I was running water directly into the exhaust horn and breathing directly into the exhaust horn. Later when I added the hoses I noticed that the resistance increased, (exactly what you'd expect considering I was exhaling through an extra mushroom valve and a hose).
I'm going to have to test the DBE in the water soon too. My suspicion however is that any added resistance will be unnoticeable, since in a horizontal swimming position double hoses exhale quite easily.
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Post by SeaRat on Jul 11, 2011 17:33:44 GMT -8
You know, I was going through the Rubicon Society website on the US Navy Experimental Diving Unit, and came upon this study of the Non-magnetic Aquamaster regulator from the 1960s. archive.rubicon-foundation.org/dspace/bitstream/123456789/3884/1/NEDU_1965_01eval.pdfThey apparently went through several different exhaust valve changes in materials of construction by USD before getting one they would accept. The more I see these graphs, the more I am glad that I bought a Mistral many, many years ago. The inhalation characteristics of the Aquamaster never did get to the Mistral's. John
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