|
|
Post by artc on Sept 18, 2023 10:46:01 GMT -8
Thanks Mark, John and Phil. This thread has shed light on the internal parts of the Fathom 50. From what I’ve read on the internet, the hp seat can be resurfaced if done carefully. That said, I haven’t heard of anyone actually having to do it. No o-rings and very few moving parts. These seem to be very robust low maintenance regulators. John, I’ll be sending you a PM soon regarding the DX Overpressure regulator.
|
|
|
|
Post by mackintoshman on Sept 18, 2023 18:30:54 GMT -8
does anyone have a parts/service manual for the 50 fathom?
|
|
|
|
Post by scubalawyer on Sept 18, 2023 19:15:07 GMT -8
does anyone have a parts/service manual for the 50 fathom? PM me your email and I'll send you a schematic and SDM article about the 50 Fathom. Mark |
|
|
|
Post by spirou on Sept 18, 2023 21:28:57 GMT -8
This is a unique downstream single stage regulator. I’ve had several, but never had to replace the seat. Is the seat leaking? If so, is it only leaking at high tank pressure? Because the spring/seat is holding back the entire tank pressure, it will leak if put on a tank with greater than 2475 psi (or maybe even a little lower). So you may not even have a problem. John Hello John, I have a question 🤔? As you write it is a downstream. When we dive with mistrals (upstream), we feel that step by step that when the pressure tank lowered mistrals are easier to breath. As I don't owned downstream single stage. Could you tell me, how it is when the pressure tank lowered. How is the felling, normally it must be harder and harder to breath, when tank pressure lowered. I have many dive with upstream single stage, I place on these regs a 3000 psi yoke and I really fell the difference between 3000, 2000,1000, and 500 during the dive, it is easier and easier to breath. I well understand that the fathom due to the downstream valve can not performed over 2475 psi. PS sorry for my English 😅. Respectfully. Fred |
|
|
|
Post by scubalawyer on Sept 19, 2023 5:47:00 GMT -8
does anyone have a parts/service manual for the 50 fathom? PM me your email and I'll send you a schematic and SDM article about the 50 Fathom. Mark Email sent. |
|
|
|
Post by scubalawyer on Sept 19, 2023 6:47:30 GMT -8
This is a unique downstream single stage regulator. I’ve had several, but never had to replace the seat. Is the seat leaking? If so, is it only leaking at high tank pressure? Because the spring/seat is holding back the entire tank pressure, it will leak if put on a tank with greater than 2475 psi (or maybe even a little lower). So you may not even have a problem. John Hello John, I have a question 🤔? As you write it is a downstream. When we dive with mistrals (upstream), we feel that step by step that when the pressure tank lowered mistrals are easier to breath. As I don't owned downstream single stage. Could you tell me, how it is when the pressure tank lowered. How is the felling, normally it must be harder and harder to breath, when tank pressure lowered. I have many dive with upstream single stage, I place on these regs a 3000 psi yoke and I really fell the difference between 3000, 2000,1000, and 500 during the dive, it is easier and easier to breath. I well understand that the fathom due to the downstream valve can not performed over 2475 psi. PS sorry for my English 😅. Respectfully. Fred At the Sea Hunt Forever shows we had about an hour of air at the 30' max depth of the Silver Springs basin with our 72's and Twin 38's. We worked in 30 minute shifts so basically we could get 2 dives off each tank. For the 1st dive on a tank many of us would use a downstream DH reg (i.e 50 Fathom) then switch to an upstream DH reg (i.e. Mistral) for the 2nd dive on that same tank. Best of both breathing worlds! |
|
|
|
Post by spirou on Sept 19, 2023 8:19:00 GMT -8
Hello John, I have a question 🤔? As you write it is a downstream. When we dive with mistrals (upstream), we feel that step by step that when the pressure tank lowered mistrals are easier to breath. As I don't owned downstream single stage. Could you tell me, how it is when the pressure tank lowered. How is the felling, normally it must be harder and harder to breath, when tank pressure lowered. I have many dive with upstream single stage, I place on these regs a 3000 psi yoke and I really fell the difference between 3000, 2000,1000, and 500 during the dive, it is easier and easier to breath. I well understand that the fathom due to the downstream valve can not performed over 2475 psi. PS sorry for my English 😅. Respectfully. Fred At the Sea Hunt Forever shows we had about an hour of air at the 30' max depth of the Silver Springs basin with our 72's and Twin 38's. We worked in 30 minute shifts so basically we could get 2 dives off each tank. For the 1st dive on a tank many of us would use a downstream DH reg (i.e 50 Fathom) then switch to an upstream DH reg (i.e. Mistral) for the 2nd dive on that same tank. Best of both breathing worlds! Hello thanks for the answer Fred |
|
|
|
Post by SeaRat on Sept 19, 2023 8:41:37 GMT -8
This is a unique downstream single stage regulator. I’ve had several, but never had to replace the seat. Is the seat leaking? If so, is it only leaking at high tank pressure? Because the spring/seat is holding back the entire tank pressure, it will leak if put on a tank with greater than 2475 psi (or maybe even a little lower). So you may not even have a problem. John Hello John, I have a question 🤔? As you write it is a downstream. When we dive with mistrals (upstream), we feel that step by step that when the pressure tank lowered mistrals are easier to breath. As I don't owned downstream single stage. Could you tell me, how it is when the pressure tank lowered. How is the felling, normally it must be harder and harder to breath, when tank pressure lowered. I have many dive with upstream single stage, I place on these regs a 3000 psi yoke and I really fell the difference between 3000, 2000,1000, and 500 during the dive, it is easier and easier to breath. I well understand that the fathom due to the downstream valve can not performed over 2475 psi. PS sorry for my English 😅. Respectfully. Fred Fred, I haven't dived the downstream Voit 50 Fathom in decades. So this is from long ago memory. Yes, it does get somewhat harder to inhale on this regulator as the tank pressure decreases. But that is somewhat offset by the very large leverage advantage of the valve mechanism, and the Venturi. With the large hole down the intake horn, once the flow is established the breathing is pretty much effortless. But cracking effort does increase as the tank pressure decreases. Fred Roberts, in his book, Basic Scuba, described this unique valve in this way:  Voit 59 Fathom 001 by John Ratliff, on Flickr I measured the breaking pressure of the Voit 50 Fathom some years ago (while I still had that mechanism) at 1 inch to 1.5 inches of water, and on hard inhalation at 1.8 to inches of water. This was on a full tank (2250 psi).  Regulator Resist Study003 by John Ratliff, on Flickr Now, nothing can beat the USD Mistral, or Voit's V-22 Polaris 50 regulators at 500 psig. Also, few realize that the Mistral, in U.S. Navy Experimental Diving Unit trials, beat out the USD Aquamaster as a breathing machine, especially at depth. Here's the EDU graph from the 1950s of the Mistral performance at depth.  USD Mistral (new cover) by John Ratliff, on Flickr Now, one other USD regulator, the predicessor of the Mistral, actually had better breathing characteristics than the Mistral, and that was the U.S. Divers Company Overpressure Breathing regulator. I have one, and have completely rebuilt it. It is a quiet regulator too, due to the Venturi hose-within-a-hose concept which pumps the Venturi air directly to the mouthpiece and into the diver's mouth via a metal mouthpiece.  IMG_1256 by John Ratliff, on Flickr John |
|
|
|
Post by spirou on Sept 19, 2023 9:11:46 GMT -8
Thanks a lot John, for your answer, with all details, and informations. It is great.
Fred
|
|
|
|
Post by artc on Sept 19, 2023 14:21:18 GMT -8
I tested my 50 Fathom at 1800 psi and 300 psi. Not much difference at all, breathes great even with the small hole facing the inlet tube. Perhaps the difference is more distinct at depth. I haven't had it in the water yet.
|
|
|
|
Post by nikeajax on Sept 19, 2023 18:11:12 GMT -8
OK, perhaps I missed it, but, why the heck were there two different 50 Fathom valve-bodies stuffed into the same can types? I mean, did people way back when realize what they were getting, or was it that you weren't supposed to look inside, so it didn't matter what anyone thought/bought? Ignorance is bliss, after all, right?
Signed,
Confused in California
|
|
|
|
Post by mackintoshman on Sept 19, 2023 18:18:25 GMT -8
I'm right there with JB. I just started learning about then. I just acquired a blue can...
|
|
|
|
Post by SeaRat on Sept 19, 2023 21:43:19 GMT -8
OK, perhaps I missed it, but, why the heck were there two different 50 Fathom valve-bodies stuffed into the same can types? I mean, did people way back when realize what they were getting, or was it that you weren't supposed to look inside, so it didn't matter what anyone thought/bought? Ignorance is bliss, after all, right? Signed, Confused in California I have a different question. The Voit 50 Fathom was designed by Emile Gagnan, but U.S. Divers Company did not produce it, Voit did. Why didn't USD produce the 50 Fathom too? Now, to answer JB's question, sort of, we divers did not know what was inside the valve. Not at all. When I took my course with LA County in 1963, we were used the book, The New Science of Skin and Scuba Diving, Association Press, New York, 1962. It covered the difference between the single stage (USD Mistral type valve) and the two stage (USD DA Aquamaster type valve). But it did not go into the difference between an upstream and a downstream single stage valve until the New Revised Edition in 1968. In that edition, there was an interesting discussion:  Fig. 22, 1 stage reg001 by John Ratliff, on Flickr Now, that is a bit of rewriting of diving history, as the two-stage regulator was the first developed by Emile Gagnan, and the single stage regulators followed later. I learned more about the mechanics of diving regulators much, much later. In the U.S. Naval School for Underwater Swimmers in 1967, where we got first hand looks and instruction in the DA Aquamaster, but had no idea of any other regulator. John *Actually, this should read: Tank Pressure............................Orifice...............................Opening Force 2,000 psi.................X..................0.01............ = ...................20 pounds500 PSI...................X..................0.01............ = ....................5 poundsWhy? Well, because if you pay attention to the units of this calculation, 2,000 pounds /inch squared X 0.01 inches squared = 20 pounds, as the "per square inch" and the "square inches" cancel each other. So on the downstream valve, the spring needs to exert 20 pounds of force against the orifice, and therefore at low tank pressure that 20 pounds of force is still there. But for the upstream valve, the leverage at full tank pressure must exert 20 pounds of force, but at 500 psi in the tank, only 5 pounds of force. |
|
|
|
Post by nikeajax on Sept 20, 2023 7:55:09 GMT -8
Perhaps Emile Gagnan had a spat with US Divers? It seems pretty stupid to use two different valve-bodies in the exact same cans, like putting a rotary engine in a car, and then an in-line four in the same model, and then people can't understand the uneven performance  JB |
|
|
|
Post by spirou on Sept 20, 2023 11:42:50 GMT -8
Perhaps Emile Gagnan had a spat with US Divers? It seems pretty stupid to use two different valve-bodies in the exact same cans, like putting a rotary engine in a car, and then an in-line four in the same model, and then people can't understand the uneven performance JB Hello It's just a theory. At this time we were at the beginning of the SCUBA, Regarding the patented and the position of Voit, and as the DW finally begin his career in 1958 (due to tractations with La spirotechnique from JYC and Rene Bussoz, remember that in Europe mistral was purpose since 1955). Voit had already his own visual, they probably try an other way, another technology, "REGULATOR COMPENSATED ", that can give an advantage, and use a patented that USD do not want. USD was also busy 1958 with the aquamaster. But another question is, why Voit decided to stop the downstream story just after three years.... Regarding the performance, and the fabrication quality, and the design. Happy divers those who can dive with the " FATHOM 50" Cheer's Fred |
|
