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Post by nemrod on Jun 29, 2006 0:24:07 GMT -8
I want way more air flow, effortless breathing and I want a pilot valve or pneumatic assist, I have several designs, I won't explain them again and I likely will never do anything about them, to many other projects.
I have in fact run out of air delievery with a well tuned and quality DA. I have not run out of air volume with any of my RAMs. For whatever reason my RAMs do provide more air and have a lower cracking effort than the DAs I have owned.
I have been known to put on an occasional burst of speed when I don't care to be where I am. When I do this I like to have available the air I need. I don't like going into O2 debt while under the water.
Both times that I recall rght now running out of air flow with a DA were head down into a current at a high work load. The same conditions using a RAM did not find me lacking. That is OK though, the only other regulator that I have ever used that could sustain my efforts was and is the Tekna T2100 so that puts the RAM in a rarified catagory for me. Perhaps some of the Apecks and AquaLung Legend would do as well.
Nemrod
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Post by Deleted on Jun 29, 2006 12:14:16 GMT -8
I have both the R-4 and the C3-N, which is an R-4 without the second diaphragm, using a flutter valve instead like the USD's.
Both units are unbalanced 1st stages, second stage has no adjustment for fine tuning. If you examine the second stage unit closely, you will find it does not match the opening for the horn.... the top of the air slot is higher than the horn opening, so air hits the side of the can first...the slot is approx. 3/4 inch wide by 3/8 high....not a good venturi....both R4 and C3 were like that.......My C3-n cracks pretty easily out of the water, but don't know how much air it will deliver underwater, but based on what I found inside the can I don't expect much. I will try it this weekend as I just aquired it........replaced the hoses with some of Bryans new repros but will try the dacor mouth piece first.......
I don't agree regarding the USD venturi.......I mod'd mine on my RAM 2nd stage to get a higher air flow which worked pretty good in Cozumel, however, the jet of air still has that short dead space to cross and some of this air stream hits the side of the can, like the Dacor.....I think a short nozzle pointing into the horn would help....maybe Luis can solve this.......he's messing with the second stage also........
By the way, I've come across a source for yellow hoses if there is any interest.........
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Post by kgehring on Jun 29, 2006 12:52:00 GMT -8
I might be interested in the hoses. Let me know!
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Post by SeaRat on Jun 29, 2006 21:15:39 GMT -8
I have both the R-4 and the C3-N, which is an R-4 without the second diaphragm, using a flutter valve instead like the USD's. Both units are unbalanced 1st stages, second stage has no adjustment for fine tuning. If you examine the second stage unit closely, you will find it does not match the opening for the horn.... the top of the air slot is higher than the horn opening, so air hits the side of the can first...the slot is approx. 3/4 inch wide by 3/8 high....not a good venturi....both R4 and C3 were like that.......My C3-n cracks pretty easily out of the water, but don't know how much air it will deliver underwater, but based on what I found inside the can I don't expect much. I will try it this weekend as I just aquired it........replaced the hoses with some of Bryans new repros but will try the dacor mouth piece first....... I don't agree regarding the USD venturi.......I mod'd mine on my RAM 2nd stage to get a higher air flow which worked pretty good in Cozumel, however, the jet of air still has that short dead space to cross and some of this air stream hits the side of the can, like the Dacor.....I think a short nozzle pointing into the horn would help....maybe Luis can solve this.......he's messing with the second stage also........ By the way, I've come across a source for yellow hoses if there is any interest......... Mossback, I now tend to agree with you. But a couple of points here. First, all these Dacor regulators could change the interstage pressure by screwing in a slotted bolt in the center of the diaphragm. You need to do that on a 500 psi source, as most of these regulators are unbalanced, as you stated. But the last one, designated the "New Balanced Two Hose Regulator" in the 1978 Dacor catelog, was the Model C3NB Balanced Two Hose Regulator, which Dacor stated was capable of 30 cubic feet per minute. Fred Roberts says that if it breaths hard, you should check the inlet filter, the "Adjusting screw (13B) located on theintermediate pressure side of diaphragm (12A) in center bolt (13A) may not have been reset to give 110 psig during reassembly," or ""Spring retainer plate (18A) ears for demand levers may have been bent causing excess friction of secondary or demand levers." I found in mine years ago that the configuration of the demand lever was wrong, in that there is a depression in the primary lever that slides down the secondary lever toward the fulcrum, rather than away (as happens with the Mistral), causing a loss of mechanical advantage. I straightened mine out (imperfectly, I might add, so that it was not a good solution) and did experience better performance in the pool with that regulator. I would not dive it in open water after that, however, as it was not a well-done job. I was going through my archieves today, looking for a paper on the original concept for the SeaFin, when I found a study of regulators I did a long time ago. So here, for the first time in publication, is my contribution. Keep in mind that I wrote this on the date below, and there are several improvements that could be made to such an experiment: July 4, 1979 ABSOLUTE MAXIMUM FLOW RATES OF SIX SCUBA REGULATORS
The absolute maximum flow rates of six scuba regulators was determined as follows:
A scuba cylinder with a rated capacity of 71.2 cubic feet of air at 2475 psi was used for the test. The cylinder had a psi gage reading of 1750 psi at the beginning of the test. The test egulator was connected to this cylinder and the valve was opened fully. The regulator was then mechanically jammed into the full open position for 20 seconds. (Some regulators show more than 20 seconds; these kept free flowing, due to venturi action, after the test time was complete.) The initial and final psi reading, and the psi differential, is listed in the table below. All regulators, except the MR-12, were two hose regulators which are currently not available commercially.
Using a factor of 0.02876868 cubic feet per psi, the following flow rates can be obtained for these regulators:
A couple of comments need to be made. First, the MR-12 was tested by pushing the purge button completely down; this was probably not a valid measurement of its absolute flow rate as the button may not have pushed the demand lever down completely. Secondly, all regulators had been tuned to perform at their best. The DX regulator was completely rebuilt, and the SCUBA Deluxe regulator had USD hoses with a straight "T" mouthpiece and a baffle plate built in. THerefore, the performances shown here may not represent what a diver who purchased these regulators fifteen years ago might experience.This backyard study was done a long, long time ago, and I probably would do it differently now. But it does give a ballpark estimate of the flow that these regulators could produce. A better way would be to begin each regulator with the same tank and same tank pressure, and let it go from there. But as you can see, the Jet Air, working from 500 psig to 175 psig, was actually one of the best performers. Only the Healthways SCUBA Deluxe and the DX Overpressure regulator were better, and they were working at higher tank pressures. Since we are talking about "Base Standard" for regulators, I thought you would like to see it. John PS--This is also a hint for the Scuba Trivia question I currently have posted on a different thread.
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Post by nemrod on Jun 29, 2006 23:41:50 GMT -8
I have done similar tests for my own amusement. The MR12 will not flow at max rate by pushing in the purge, at least mine do not. Neither do the Tekna or several others I have. I think you will need to manually deflect the diaphram for max performance.
Maximum flow values may not actually represent breathing ease during normal diving or represent "work" of breathing but the results are interesting.
James
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Post by duckbill on Jun 30, 2006 0:58:40 GMT -8
A Jet Air is a DW Mistral. I wonder what caused the difference. It would be interesting to do the same test but using the same starting pressure on these two regulators.
Mike, I think a "base standard" can be whatever you want it to be. It is just a standard against which others are compared and contrasted. What I have been seeing on this thread so far is an attempt to name the "ultimate standard". But, it seems the thread is heading in a direction with which you are happy. Interesting reading.
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Post by Deleted on Jun 30, 2006 6:28:45 GMT -8
John
That's interesting info and useful to a point which I will try to address below.......Terry, the direction you mentioned is very interesting and I am starting to come to an conclusion that the Standard for a New Doublehose should be a accumulation of both old and new........old, the best features of the best doubles (since they are no longer manufactured, the New Mistral not with standing) and the new (single hose standards)
Bear in mind a lot of the new single hoses that "quote" lead the pack "unquote".....have a lot of gegaws that are probably not necessary and are just something else to break..........
I think, (please comment on this) the holy grail of doublehoses would be performance that signifiantly reduces the hard breathing of the head down decending position..this is the biggest negative I believe these regs suffer.....I don't know at this time if better air flow (read that as higher flow volume) will help this.
Using all silicon parts for better sensitivity will help, however, I do not see silicon parts pushing air down the intake hose any better.
The inside diameter of the standard hose used on the RAM and DAAM is approx 1 inch. What is the inside dia. of the new flex hose Dan is selling? Is it larger? What is the inside dia. of the New Mistral.....wall thickness of Dan's new hose?
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Post by SeaRat on Jun 30, 2006 7:50:17 GMT -8
Mossback, Concerning the differential in pressure, there are basically two ways of dealing with that. The first, which has been mentioned a lot, is with the regulator position. Obviously, we've discussed getting it as low as possible on the diver's back, or chest-mounting the regulator. The low position on the back needs longer hoses to work, and these currently are not readily available. I put SCBA hoses on my DX Overpressure Breathing regulator, and that worked very nicely to allow the regulator to go down on my back. Here is a photo of a diver at the US Naval School for Underwater Swimmers, in Key West, FL in 1967 using twin tanks with the regulator in a good position for breathing: The Cousteau team used the chest-mounted regulator on their Conshelf III project, and that apparently worked well for them. One other possibility is to use on offset position on the tanks. Cousteau did this on one of his expeditions, where they used triple tanks with the regulator mounted on the right side tank, and they extended the exhaust hose to do it. This allowed the diver to regulate the position by rolling a bit onto his right side, which aligned the regulator to the center of the lungs. I have experimented with this using a set of twin 50s with only a K-valve on each tank, and separate regulators. I used my DX Overpressure Breathing regulator for this, as it has long enough hoses to account for the lengthened distance, and the hose length does not affect the breathing with this regulator (see the discussion below about that). I found that it was a very nice way of mounting the regulator. Others (Dr. Lundy) have put together a triple set with the USD manifold that mounts on the right side tank, and used double hose regulators with that. Concerning the DX regulator, it has a "hose within a hose" concept, where the venturi air is piped in a small interior hose directly to a metal mouthpiece. There, it is re-directed through several holes in the metal tube in the mouthpiece right directly down the diver's thoat. This is the venturi concept which really puts the venturi in the mouthpiece, with almost no hose loss as the small inner hose is smooth, and has a lower volume. This venturi air then drags th diaphragm down, and secondary air is sent through the outer hose. This is also about the quietest double hose regulator ever built. But USD provided very short hoses, and they tasted bad, so this was replaced very shortly by the DW Mistral. Here is an absolutely terrible photo of me (self-portrait) using that regulator with the metal mouthpiece: Here is another photo showing the regulator with the longer hoses: Finally, there is one other concept which has never been implemented that I know of--the weighted diaphragm. I have a paper somewhere that discusses the possibility of either weighting the diaphragm, or putting a lever onto the diaphragm with a weight on the end to weight it in certain positions (on the stomach, face down), and remove weight in other positions (on the back, face up). What this would do is to weight the diaphragm so as to simulate the actual position at the center of the diver's lungs. But nobody has implemented this concept. The closest I've seen is the Scubamaster regulator (I think) which had a weighted exhaust mushroom valve so that it could be tuned very finely without the potential of water-differential leakage when the diver was upside down (this was a single hose regulator). John
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Post by Deleted on Jun 30, 2006 9:23:43 GMT -8
John
How much weight would be required to displace the equlivant of 4 inches of water against the diaphgram?
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Post by luis on Jun 30, 2006 10:14:18 GMT -8
4 in WC (water column) = 20.8 pounds/ square foot = 0.144 psi
Just multiply it by the area of the diaphragm (in the corresponding units).
Area of RAM diaphragm: D = 4.25 in
A = (Pi / 4) x (4.25”)2 = 14.18 sq in
W= 14.18 in2 x 0.144 lb/in2 = 2 lbs
That seems too high, but then 4 in WC is quite high and our DH diaphragms are intentionally big to give mechanical advantage when converting from pressure to force (a little pressure converts into large force/weight).
You could use weights or springs to pressurize the system (regulator, hoses, lungs, etc.) to the lowest point in the water column were the divers lungs are located, but your exhaust will need to back up that pressure or you will get a constant free flow.
In other posts I have mentioned about an engineer ex-coworker of mine (close to 20 years ago) who worked on a zero differential pressure diving suit. The suit tried to use some of the same functional principles as an Air Force G suit. It was intended to eliminate the work of breathing for long duration dives (commercial & military). It worked but it was too complicated and too much trouble.
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Post by SeaRat on Jun 30, 2006 10:27:16 GMT -8
Mossback,
That would be (using salt water at 0.445 psi/foot) 0.1483 lbs/in2. Multiply that times the area of the diaphragm and you will have your answer. For instance, if the diaphragm is six inches in diameter (this is a guess, as I'm at work and cannot measure it), the area is pi x radius squared, or 3.1415 x 3 squared (the surface area of the diaghragm), or 3.1415 x 9 inches squared x 0.1483 lbs/inch squared = 4.19 lbs = 4 lbs (rounded). This may be why no one has tried it!
It is theoretically possible to balance the diaphragm to the same pressure as are inside the lungs. I actually think that the lever system may work best, with the lever extending down between the two tanks for a twin-tank setup.
The disadvantage is that, with the system on, a diver's movements (especially out of water) would trigger an immediate response on the regulator, and there would be free-flowing happening.
John
PS--I just saw Luis' post (almost exactly the same time as mine), and apparently the diameter is 4.25 inches, which accounts for the difference between our calculations. The calculation would also be much different on a Trieste II, as it's diaphragm is much smaller (somewhere around 3").
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Post by Deleted on Jun 30, 2006 10:42:12 GMT -8
John/Luis......I can see why that has never been developed....I had an engineer, who has been mentoring me here at work on my Dacor's, do a quick sketch and we came up with a method.....but not with THAT much weight......scrap that idea..... Looks like physics has won again short of some fancy device, that James probably has developed and is keeping secret .....I still think current regulators old and new doubles do not deliver all the air provided in a efficent mannor thru their hoses.........time will tell I guess....... thanks guys for y'all's input.......it has been greatly appreciated.
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Post by nemrod on Jun 30, 2006 11:36:50 GMT -8
The super stretch hose upon examination is of the same internal diameter. I think the air flow "sees" a smoother internal surface due to the higher number of corrugations than the standard hose and this alone explains the possible/perceived easier breathing.
The new Mistral really has no aspects beyond LP and HP ports I find worthy of having. It is an abysmal failure. Virtually nothing of what it should have been and mostly everything of what is not--a fancy plastic single hose and a poor one at that. I have to say, the hoses and mouthpiece alone make it a fialure out of the gate, using one is like being pummled by Mike Tyson and in the end, much like him, much tadoo over nothing. Nemrod
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Post by broxton on Jun 30, 2006 13:55:17 GMT -8
Lets hear more about those yellow hoses!
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Post by nemrod on Jun 30, 2006 15:46:28 GMT -8
"Looks like physics has won again short of some fancy device, that James probably has developed and is keeping secret"
I don't know, better look to Luis for the secret skunk works, my shop is mostly full of bits of aluminum and pieces of Lycoming.
"Lets hear more about those yellow hoses! "
Only thing I want to hear is where and how much!!!!!!
I think me and Luis discussed via phone once using a spring to preload or balance ambient to allow the back mounted regulator to respond as if it were at the same pressure position as the lungs. I think this might work but is not an ideal solution and would predispose the regulator to freeflow possibly controllable via a vane or adjustable preload from zero to freeflow condition so it could be adjusted to fit the need.
I wager a bet that the next big jump in diving regulator design will be electronic/computer control. You may doubt me now but just wait and see!! A programable chip with a learning function could totally repalce the majority of mechanical diaphrams and levers and pistons and springs. About a year ago Mares was going on about their new to be released gear would be revolutionary---ho--hum--yeah right. BUT, I do think some enterprising company is probably working on this now. Electronic digital controlled regulators and see in zero viz "sonar" masks are coming --eventually. Don't believe me, I just bought a Humminbird 987c side scan sonar for my boat. It "sees" underwater producing picture like results. This technology can be adapted to a LCD screen in your dive mask.
Will you ol'fogeys go for it--well---I still stand on the edge of the razer, one foot in the modern world and one in the past. You know your old when the past is all you think about, I think about the future (and hope I will be there--lol) and I think vintage could have an impact on the future of diving equipment design. I think that my "FADEC" controlled regulator might more easily resemble a double hose than the cumbersome two piece hub cap in the mouth single hose. A breathing robot that monitors your demands, factors in the ambient conditions, knows your typical requirments and can respond instantly--that is the future base standard.
Nemrod
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