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Post by vance on Nov 30, 2023 9:23:18 GMT -8
I just picked up another Dacor regulator. This one is an R-4, which is a lot the same and a bit different than the C-3 I recently posted about. I will post some photos of the rebuild when I receive it. The R-4 continues the two diaphragm system that characterized the early 2500 series double hose regs. These sport 2 full size diaphragms, but one has an exhaust mushroom in the center. Dacor's reasoning was that redundancy was a good thing, and the exhaust diaphragm would work sufficiently, in case of failure of the intake diaphragm. The most noticeable effect is less than stellar exhaust effort, which was partly the cause of the R-4's failure to pass US Navy approval requirements. It also failed the inhalation requirement. This photo is an exhaust diaphragm with the exhaust valve mount in the center. Intake diaphragms are identical, but no provision for the mushroom valve.  The photo below shows the exhaust horn ring that is not found on most other late model Dacor DH regs. The exception is the C-3N which has the ring, but used a duckbill valve rather than the second diaphragm. I suppose Dacor had a bunch of R-4 parts left over....  The top box, valve body, levers, second stage, etc., are the same on all Dacor DH regs after the 2500s.  More to follow! |
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Post by SeaRat on Nov 30, 2023 10:05:18 GMT -8
Dacor made a mistake with their exhaust diaphragm. They actually cut down the surface area of the exhaust with their newer diaphragm rather than increased it. Here's the calculations I made, and have shown here some years ago.  IMG_1699 by John Ratliff, on Flickr  IMG_1701 by John Ratliff, on Flickr The older diaphragm was at 231 square millimeters to 210 square millimeters of area on the newer diaphragm under the exhaust mushrooms. That is probably why the exhaust did not meet the U.S. Navy Experimental Diving Unit's requirements for exhausts. If they had added three 7mm holes between those rectangular openings, they would have increased this surface area to 325.5 square millimeters, and significantly improved the exhaust output. I did something different, in that one of our members has produced silicone exhaust diaphragms, and those have the some opening as a USD Conshelf/Calypso (late models) in the exhaust. So mine have the improved exhaust. John |
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Post by vance on Nov 30, 2023 17:07:37 GMT -8
An R-4 equipped with a duckbill (either NOS Dacor or reproduction USD) without the second main diaphragm will work equally as well as a C-3N.
There is a report from the US Navy that outlines the failure of the R-4. Is there another report concerning the C-3N?
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Post by Tusker on Nov 30, 2023 17:18:11 GMT -8
Could you do something similar to bypass the exhaust diaphragm, for whatever reason you might want or need to, with the 2500 series regulators?
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Post by vance on Nov 30, 2023 17:42:30 GMT -8
Could you do something similar to bypass the exhaust diaphragm, for whatever reason you might want or need to, with the 2500 series regulators? Sure! Just leave out the exhaust diaphragm and put a duckbill in the exhaust horn. It'll breathe (exhaust) way better than the original. Exhaust effort costs more to the diver than intake does. This is what Dacor did with the C-3N. It has the same parts as the R-4, but they left out the second main diaphragm, and used a duckbill instead! |
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Post by SeaRat on Nov 30, 2023 21:26:11 GMT -8
Could you do something similar to bypass the exhaust diaphragm, for whatever reason you might want or need to, with the 2500 series regulators? Sure! Just leave out the exhaust diaphragm and put a duckbill in the exhaust horn. It'll breathe (exhaust) way better than the original. Exhaust effort costs more to the diver than intake does. This is what Dacor did with the C-3N. It has the same parts as the R-4, but they left out the second main diaphragm, and used a duckbill instead! 'Probably want to place a rubber gasket between the two pieces (the exhaust horn and the face) so as ta have a better interface without the diaphragm. I don't know of a C-3N evaluation though. John |
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Post by vance on Dec 1, 2023 8:05:02 GMT -8
As John points out, a gasket (or flange out of a bad diaphragm) would need to be used.
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Post by Tusker on Dec 1, 2023 8:35:41 GMT -8
Great to know, thank you! I ended up with two new regulators unexpectedly, one of them is a R-3 and I would like to dive it at some point. It has a hiss through the mouthpiece when under pressure. Maybe the HP seat? It has the original small mouthpiece, but there's a crack in one of the hoses. I've just moved and don't have my tools yet, but I'll make a thread about it once I get the chance to break it down and look at the internals.
Jacob
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Post by vance on Dec 1, 2023 9:17:36 GMT -8
The R-3s second stage is very different than the R-4 and up regs. There's a long (maybe several) thread(s) about them.
The IP tends to be too high on these, in my experience. On mine, the IP has always been at about 160 psig. There's no adjuster, so you are stuck with what it is w/o some serious hoop-jumping. An adjuster from a later model will work in these (untested in actual use) if the center hole of the HP diaphragm is enlarged.
The second stage is a PITA to get leak-free, esp with a high IP value. There's also the LP seat problem.... All this is agonized over in the relevant threads!
I don't know if I discussed the following situation elsewhere, so this might be the time and place. There are replacement HP diaphragms offered by TSM and another store. When testing Rob's prototypes, I found the IP way too low due to the durometer of his material. This required shims to boost IP. He has since found better material, but I haven't tested it yet. He has put them on the TSM site, so they must be working to his satisfaction.
The other store offering replacements (I can't remember the name) also offers shims, which makes me believe the durometer isn't correct on theirs. This is really only a problem with the 2500s since the later models have adjusters.
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Post by SeaRat on Dec 1, 2023 9:27:36 GMT -8
Now that the Rubican Research Repository is gone, I've found another way to get some of the Navy Experimental Diving Unit (NEDU) reports. I go to Google Scholar, and type in the request. I just did that for "Dacor R-4," and guess what? I got the NEDU report on the Dacor Diving Lung with Dial-A-Breath feature. apps.dtic.mil/sti/pdfs/ADA040145.pdfHere's what it states about Navy approval: This is a multi-page document with graphs of he breathing resistance included. There is also a second evaluation report available, and here is that link: apps.dtic.mil/sti/pdfs/ADA037004.pdfJohn |
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Post by vance on Dec 1, 2023 12:05:28 GMT -8
I'm assuming this is a report of the R-3 series, not the other later models with Dial a Breath.
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Post by SeaRat on Dec 1, 2023 16:20:26 GMT -8
I'm assuming this is a report of the R-3 series, not the other later models with Dial a Breath. Phil, The first link is to the report (kinda brief) on the R-4 and Olympic regulators. The second (which I sent you via e-mail in PDF format) and third, which I quoted and has the link, was about the Dacor R-3, which was evaluated, rejected, then re-evaluated. Note that the R-3 was evaluated with both the Dial-A-Breath feacture set to "Easy" and "Hard." In the first evaluation, on the "Hard" setting, the graphs show that the regulator was way over the NEDU limits. Here's the search I made, which brought up a bunch of other interesting studies. scholar.google.com/scholar?hl=en&as_sdt=0%2C38&q=Diving+Regulator+Evaluation&btnG=John |
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Post by james1979 on Dec 1, 2023 17:59:45 GMT -8
As John points out, a gasket (or flange out of a bad diaphragm) would need to be used. That would be a quick easy print in TPU.... |
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Post by vance on Dec 2, 2023 7:54:32 GMT -8
You’ve made me one or two already, James!
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Post by james1979 on Dec 2, 2023 8:31:17 GMT -8
I'm contemplating sending Jacob some printed stuff for the Dacor's if he's down to try them out.... one of the C-400 covers and an attempt at the R-4 exhaust ring DBE.
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