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Post by SeaRat on Jun 21, 2021 17:50:33 GMT -8
For decades, the way we vintage divers dived was sans the submersible pressure gauge (SPG). Why? Well, because it really had not been invented and popularized yet. In the USAF, we had our jump tanks, and they were equipped with a 500 psi J-valve on the manifold. When breathing got hard, we tripped the J-valve and surfaced. Here are a few photos from way back. John Photos003 by John Ratliff, on Flickr Here, I'm diving our jump tanks (the tanks we used for parascuba jumps in the USAF). I'm in Alexander Springs State Park, in Florida above (north of) Orlando, Florida. DA Aqualung-2 by John Ratliff, on Flickr Here's the double tank U.S. Divers Company twin manifold with a 500 psi reserve. Pulling this reserve would give you anonther 250 psi in each cylinder. The nice thing about this is that in equalizing between the two tanks, there was a noise associated with it that informed a buddy that you were on reserve. Note that the lever is up when the resere is "On," and down when it has been tripped. Many disliked this configuration in that it could be inadventently bumped and therefore "tripped" without the divers knoweldge, and when the regulator began breathing hard, the diver would try to trip the reserve, and find that (s)he was completely out of air. _MG_5130 by John Ratliff, on Flickr The Cousteau original system withheld the entire contents of one of the triple tanks as a reserve. When breathing became difficult, the valve was turned, and the entire contents of this tank equalized between the other two tanks. This created quite a noise, and especially in tropical areas (where Cousteau's team originally dived), informed buddies that this diver was on reserve. Since these tanks were small, and came out to only about the equivalent of our 80 cubic foot tank, only about 25 cubic feet of air was in reserve. One way of overcoming the inadvertent tripping of the J-reserve was to reverse the lever's orientation. Some manufacturers allowed this in their J-valve design: IMG_1022 by John Ratliff, on Flickr Or, as in my case, the diver himself with a twin manifold could simple reverse the orientation of the J-reserve from the left to the right shoulder, and thereby reverse the orientation of the J-reserve lever. IMG_1456 by John Ratliff, on Flickr We used to be able to obtain a very simple addition to the band that captured the J-reserve pull rod, if we had this reversed orientation. IMG_1457 by John Ratliff, on Flickr IMG_1454 by John Ratliff, on Flickr This "L" shaped metal strip with a hole also helped with the jump tanks we had if the bands had no J-valve cut-outs. The U.S. Divers Company UDS-1 system had a triple tank manifold with a J-valve, set I think at about 750-800 psig. It was located behind and below the diver's rear, and so could not be inadvertently tripped. The diver had to do so with his left hand. UDS1bal by John Ratliff, on Flickr UDS-1 Valve inside case by John Ratliff, on Flickr Some manufacturers provided a regulator with a J-reserve built in. White Stage Manual BC-1 by John Ratliff, on Flickr When attached to a twin tank manifold, it was protected from inadvertent tripping, and also provided a 300 psi reserve to both tanks, which was greater reserve air than the 500 psi reserve on one tank for the twin tank manifold (250 psi in each tank after equalizing. There has been a lot of discussion against the J-valve in current diving and instruction, but I thought I'd provide some of the history and advantages of this design. In zero visibility, you cannot even see a SPG, and this really does work to tell the diver when he or she is low on air. John
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Post by luis on Jun 21, 2021 18:38:56 GMT -8
It is true that the “underwater pressure gauge” or “submersible pressure gauge” did not become popular right away, but it was around longer than most divers realize.
The “underwater pressure gauge” is shown in page 8 of the 1957 US divers catalog. I am fairly certain, that is less than a decade since the Aqua Lung was introduced in the US (or just close to it).
I always hear that Sportways introduced the “Sea-VUE” to the Scuba market in the US, but the earliest Sportways catalog I have is 1961. In that catalog you can already tell that it was a very mature offering. They are showing it with every regulator.
BTW, one neat trick about an SPG with the standard swivel is that you don’t need to see it to determine if the pressure is below 1000 psi. If the swivel is hard to rotate, you have more than 1000 psi, but if it is easy to rotate you have less than 1000 psi. I am not sure how precise, but it seems to be fairly repeatable. It is just a trick someone showed me and it seems to work.
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Post by vance on Jun 21, 2021 18:52:19 GMT -8
BTW, one neat trick about an SPG with the standard swivel is that you don’t need to see it to determine if the pressure is below 1000 psi. If the swivel is hard to rotate, you have more than 1000 psi, but if it is easy to rotate you have less than 1000 psi. I am not sure how precise, but it seems to be fairly repeatable. It is just a trick someone showed me and it seems to work. Huh. That’s really good to know!
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Post by SeaRat on Jun 21, 2021 20:18:00 GMT -8
I started this thread because I looked over our history here, and didn't see any real discussion of the J-reserve. I saw references to it, but no real discussion. Luis, you mentioned determining if the pressure in the scuba is below 1000 psi by determining whether the SPG rotated easily or hard. Well, some of the early ones didn't even ratate. And, I have one set of tanks that is 2100 psi, and another that is 1800 psi. That would only tell me that I was almost half way down on my air supply. And it would not give any difinative warning of impending out-of-air. So, for me, it's not too useful. Also, as you know, the U.S. Navy was not to thrilled about the use of a SPG in 1967 when I went through their U.S. Naval School for Underwater Swimmers, as it wasn't even mentioned in the weeks I was there. The March 1970 issue of the U.S. Navy Diving Manual makes no mention of the SPG either (actually, they also don't mention single hose regulators too). So the SPG wasn't really catching on until the mid-1970s, in my estimation. I know that Larry Murphy required both SPGs and octopus regulators during our diving at the Warm Mineral Springs Underwater Archaeological Project in Florida in 1975. But my 1973 NAUI instructor course did not require octopus regulators. However, Daniel Lenihan, in his publication "Underwater Archeorlogy in the National Park Service,"* stated on page 73 under "Equipment Requirements": He also mentioned that buddy breathing drills and the use of a BCD were required. There is no mention of an octopus in this publication. And, the National Park Service required rescue training for all their divers. Divers used their computed air consumption rate (surface, translated to depth) and watch to determine when they were getting close, but that did not do anything for an increase in demand due to unforeseen circumstances (current, depth, picking up and hauling something, etc.) So the J-valve is still in my mind useful. Here is a video where I used my J-valve solely with my Healthways Scuba Hybrid regulator (equivalent, or better than, the Mistral) to determine when I needed to terminate the dive. This is a rather long video of lampreys spawning, but toward the end, at the 39:51 minute mark, I talked about needing to surface because I pulled my J-valve. Listen to it from about 39:30 on, and you can see that I was mesmerized by the second spawning event, and then had to go because of the J-valve. Now, I'm wondering whether any of you dive with a J-valve only for your vintage dive? Most of us have figured out how to use modern regulators along with our vintage regulators (I have two double-post manifolds now). But I'm curious whether any of you still use the J-valve only option for diving? John PS, here's my equipment configuration for the Lamprey Spawning, second dive: John with PJ tanks on Lamprey Video by John Ratliff, on Flickr Note that this set of doubles has the J-valve on the other side, so it cannot be inadvertently tripped.
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Post by duckbill on Jun 22, 2021 0:22:17 GMT -8
I will never again entirely trust a J-valve on a manifold. I love my J-valves, but I learned my lesson.
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Post by scubalawyer on Jun 22, 2021 4:51:13 GMT -8
I'll do a J-valve only dive every so often. All 24+ of my SHF dives in Silver Springs have been J-valve only with two 30 minute working dives on each tank and usually a required reserve pull at the end of dive #2. I have J-valves on single tanks that do work at 300 psi (ish) and on dual manifolds at 500 psi (ish). Several of my J-valves just never kick in at any pressure regardless of my attempts to rebuild. Because of that "failure" rate I've tested each valve with a SPG and breathed the tank down to see if/when the J-valve kicks in. After several "good" test runs I'll trust that particular J-valve (combined with use of a watch and known start pressure in my tank of course ) Otherwise, a SPG is my friend.
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Post by SeaRat on Jun 22, 2021 7:51:52 GMT -8
I will never again entirely trust a J-valve on a manifold. I love my J-valves, but I learned my lesson. There's got to be a story behind this statement. John
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Post by snark3 on Jun 22, 2021 10:38:48 GMT -8
John- When I got my NAUI certification in 1975 the SPG, octopus, and BC were not required equipment. My buddy got PADI certified in 1979 and it was required in his class.
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Post by nikeajax on Jun 23, 2021 7:52:04 GMT -8
I have the reg mounted on a j-valve, but if you look closely, you can see that the Healthways Divair had its own version of a reserve valve, mounted on the right side: As Skip is the only one I know with a Northill, he'll have to verify this, but I seem to recall, the Northill had the same type of reserve too. What's interesting about the HW is that it was adjustable. JB
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Post by surflung on Jun 23, 2021 12:00:56 GMT -8
I am proud to say I have every one of my J-Valves serviced and working properly. SeaRat John... You got me interested in this way back in 2013 or so. My buddy Rich was diving with his Spare Air unit attached and it seemed silly to me because we never minded running out of air back in the days of relatively shallow lake diving I did in the 1970s. Having got back into diving after many years away from it, I was surprised at how many modern divers had never experienced running out of air. We used run out often and when we did we just came up.
But then we started diving vintage in Fortune Pond and getting down to depths of 80-130 feet... Running out that far down would mean quite a long swim... not to mention a free ascent. And so I became interested in my reserve valves. And John, you made a comment that put it in good perspective for me. You said the reserve valve was like carrying a Spare Air without having to carry a Spare Air. It also means you don't have another dangling hose to manage an SPG.
The local dive shop kidded me about my "Suicide Valve" but then I think it was Luis who said Reserve Valves are still used by commercial divers and recognized or required by OSHA in some commercial diving situations. So there!
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Post by SeaRat on Jun 23, 2021 17:59:40 GMT -8
Ebon, Thank you for that post. Concerning the OSHA Commercial Diving Regulations, here's what they currently state: Now, for everyone, here's some information on J-valves you may never have heard before. IMG_1464 by John Ratliff, on Flickr Here is an interesting setup. I have a 300 psig J-reserve on my Calypso-J regulator first stage, and a 500 psig reserve on the manifold. This is a double reserve, without any outside obstructions. Each of these cylinders is 52 cubic feet. A 500 psig manifold withholds 500 psi/1800 psi, or 28% of the one cylinder. That's 28% of 52 cubic feet of air, or about 14.4 cubic feet of air from the manifold. The center post, if the manifold is down, at 300 psig withholds 300 psig/1800 psig, or 17% of the air in both cylinders, which is 104 cubic feet with this setup. With this setup, and the manifold reserve down (no reserve), the center post J-reserve first stage holds back 17.3 cubic feet of air, which is more than the doubles manifold. Now, combine the two, and you get 31.77, or almost 32 cubic feet of air withheld by J-reserves. This is 31% of the air available, or just about equivalent to the Cousteau original triple tank system that withheld 33% of their air supply. But those triple tank systems did not have even as much air as the twin 52 cubic foot tanks. Now, apply that to twin 72s. Each of these cylinders is 52 cubic feet. A 500 psig manifold withholds 500 psi/2475 psi, or 20% of the one cylinder. That's 28% of 71.2 cubic feet of air, or about 14.38 cubic feet of air from the manifold, or about 14.4 cubic feet of air. The center post, if the manifold is down, at 300 psig withholds 300 psig/2475 psig, or 12% of the air in both cylinders, which is 142.4 cubic feet with this setup. With this setup, and the manifold reserve down (no reserve), the center post J-reserve first stage holds back 17 cubic feet of air, which is more than the doubles manifold. Using both J-valves allows about 31.4% of the air to be withheld, or 44.71 cubic feet of air to be withheld. Now note that I have a small parachute cord tide to the center-post first stage J-reverve lever. This would allow someone to pull the J-valve for this first stage from behind and below the twins, where it is completely protected from inadvertent tripping. Now, there is another trick I'd like to show you, and that is the bird-nest coil. We learned this from the U.S. Air Force Pararescue Transition School, where we bird-nest coiled our let-down tape (a nylon tape 250 feet long, with at least a 2,000 pound breaking strength). The bird-nest coil was actually developed by U.S. Forest Service smokejumpers, and the USAF learned it from them. This letdown tape allowed us to land a parachute in a tree, and let ourselves down from the tree using this let-down tape. We would tie it to the risers of the hung-up parachute after threading it through two D-rings at our waist. Once it was tied, we could use our Capwell quick releases on our risers, and cut ourselves from the parachute. Then we simply rappelled out of the tree, using the 250 feet of let-down tape which was bird-nest coiled into our right tree suit pocket on the trousers. NCSB Jump003 by John Ratliff, on Flickr When I was smokejuming in 1972, my partner, Larry Longley, got a hangup and had just reappelled out of a large tree when I took this photo. I had just gotten to him, and confirmed that he was okay after hitting these trees so hard. I had landed in a clearing about, where winds were less strong. NCSB Jump001 by John Ratliff, on Flickr Here's the hangup Larry got, by his suspension lines because he went through about five trees in high winds before hanging up. The jumpmaster in the plane thought he was most likely hurt and was getting ready to drop the first aid kit before I sent the signal up with a double-L ("LL") signaling that he was fine. In this photo, you can see Larry up in the tree with a handsaw to top the tree, and free the parachute from the tree's top. The letdown tape is what I'm using to pull the parachute away from the tree so that went Larry sawed it off, it would not land on him. Here's what a bird-nest coil looks like in miniature: IMG_1466 by John Ratliff, on Flickr Pull the line out of the last look, and the entire bird-nest coil can be released by simply pulling on the end of the cord (or let-down tape). This bird-nest coil is started with about 5 loops of line, then putting the thumb on the line, pulling a loop up to the top, then pulling another loop from the opposite side, and using the line to make a new loop from the opposite direction which goes into the first loop. Then it is simply continued until all the line is used up, and the far end is finally pulled through the last look to safety the bird-nest coil. It can then be thrown around, and will not unwind until that last end is pulled out of the look, releasing the bird-nest coil for use. By the way, you can secure the bird-nest coil at any time by pulling the end through the last loop. That is what I did to provide a "handle" for pulling the reserve in the center-post setup above. John
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Post by snark3 on Jun 24, 2021 10:29:11 GMT -8
JB is correct, Northill double hose regs do have a reserve built in.
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Post by duckbill on Jun 24, 2021 11:03:16 GMT -8
I will never again entirely trust a J-valve on a manifold. I love my J-valves, but I learned my lesson. There's got to be a story behind this statement. John I was diving the river and my j valve started to activate while I was swimming through the branches of a fallen oak tree. I pulled the rod and had no reserve. I found out that the steel ball in the old style US divers manifold had a small leak to it. I usually breathe very slowly while diving, and between breaths was enough time for enough air to leak past the ball to keep both cylinders equalized, not holding back a reserve in one of them. This was mentioned a while back in an old thread. vintagescuba.proboards.com/thread/3723/valves-supposed-leak?page=1Also, I'm a bit surprised that stacking j valves would give a reserve of each added together. I'd have to think through it, but it seems that the maximum reserve possible would be that yielded by the weakest link, meaning the highest reserve. In other words, a 300 psi reserve on a 500 psi reserve manifold would give a maximum reserve that the 500 psi reserve alone gives, and the 300 psi reserve just giving an additional step warning at 300 PSI. Or am I missing something?
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Post by SeaRat on Jun 24, 2021 11:19:54 GMT -8
Terry,
I"m going to re-think the stacking of reserves too. I'll keep you posted.
John
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Post by james1979 on Jun 24, 2021 11:37:12 GMT -8
Also, I'm a bit surprised that stacking j valves would give a reserve of each added together. I'd have to think through it, but it seems that the maximum reserve possible would be that yielded by the weakest link, meaning the highest reserve. In other words, a 300 psi reserve on a 500 psi reserve manifold would give a maximum reserve that the 500 psi reserve alone gives, and the 300 psi reserve just giving an additional step warning at 300 PSI. Or am I missing something? If I read the process right, based on what I've seen out of my Sherwood J-valve, the manifold J is withholding 500 psi on that one tank... so really, the first 500 psi will come off of one tank (I base this off of the fact my J valve will read 300 psi "low" until I pull the rod). So once the non reserve tank is at 1300, the reserve side is at 1800 and starts sharing the load (just staying 500 psi higher). When the pressure reaching the Regulator is at 300, the reserve side tank is at 800 and non-reserve side is at 300. Regulator J-valve gets pulled, and you keep breathing that 300 both tanks (full dual tank 300 psi reserve). In theory, you breathe that down to empty (as felt by the regulator) and you are at 0 on the non-reserve side, but still 500 on the reserve side. Pull the manifold reserve, and the tanks equalize at a 250 psi reserve. I think. Respectfully, James
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