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Post by SeaRat on Oct 9, 2006 19:41:32 GMT -8
I started this discussion on the General Discussions, under the topic of the oval mask. But it deserves its own thread here, as it is a technique that was used by vintage divers to ensure that the J-reserve valve mounted on double tanks worked. What we did was to reverse the manifold, and place it on the right cylinder instead of the left cylinder. Normally, this is what the valve looks like in this photo from the Sherwood catelog for one of the valves prized by vintage divers today, the Model SVB 4000 JD wiht reserve: Note that the lever arm for the reserve sticks out away from the diver. This configuration allows the tanks to be bumped, and to trip the reserve without the diver knowing about it. But with the reversed valve, as you can see in on my twin 45s, it is on the right cylinder and pointed towards the diver's back. If the cylinder is bumped, it does not trip the J-valve. I found that I was not the only one doing this when I looked at old photos from John E. Kenny's book, Business of Diving[/B], Book Division, Gulf Publishing, Houston, Texas 1972, pages 192-193: These two divers have differently configured J-valves. Note that on the lower diver, the set of tanks has the J-valve in the reversed position. Here these two UDT members have their valves configured in the reversed position, with the reserve lever pointed toward their body. I wanted you to see this, as I have been diving it for over twenty years now, and never have experienced the inadvertent tripping of a J-valve that these valves are famous for with this configuration. John
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Post by duckbill on Oct 9, 2006 20:57:14 GMT -8
I've noticed that on the television show "Flipper". I also noticed that they didn't use the rod. So, I would think that the valve must be more accessible by hand when in the reverse postion you describe. The problem is that it is hard to find a backpack which is designed to allow the use of the rod in that configuration. The old ScubaPro single cylinder backpacks with the 'knife handled' cam on the tank band seem to have the clip in a position which would necessitate the j-valve to be on the standard side (obviously can't turn a single cylinder valve around ), but with the handle pointing forward. Funny how the other guy in the escape hatch has his in the standard configuration. In the Marines, everything was about "uniformity, uniformity..."
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Post by SeaRat on Oct 9, 2006 22:23:52 GMT -8
Duckbill, We did not use the rod in the Underwater Swimmers School (USS) either, even with the standard configuration, nor did we use it in the USAF with our jump tanks (too easy to hang up a riser or parachute line if we tumbled). The funny thing is, I don't ever remember running out of air either, except on recreational dives. The twin 90s in USS held a huge amount of air, enough for a 1500 yard underwater swim with air left over. Recreationally in the USAF, we used twin 72s for our dive tanks when not doing a parascuba jump, and we used the standard configuration of the reserve valve and did have the pull rod. I do use the pull rod now, with the reverse-mounting of the double tank manifold. I also have a metal "L" with a hole for the rod in the short end, and the long end goes under the lower tank band. So it stays in place, even though the tank band inserts for the J-valve rod are not used. Also note that the single cylinder J-valve cannot, except for the Scubapro DCAR valve, be placed in a different configuration as the regulator would then be backwards. The Scubapro valve designated the DCAR valve with gauge (for Depth Compensated Adjustable Reserve) was designed to be reverse-mounted too (see below). However, most dive shops would only configure it for the normal position, and they also would not use the option of having a 600 psi reserve setting rather than the normal 350 psi (300 psi for other manufacturers). Just another option to throw out there. I have one, and I need to set it up this way too. This was done by Scubapro in response to requests from the cave diving community, as I recall. Belowm is the 1976 Scubapro catelog, page 38: John
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YankDownUnder
Pro Diver
Broxton 'green label' Aqua Lung and 1954 USD Rene triple 44s.
Posts: 162
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Post by YankDownUnder on Oct 9, 2006 22:52:53 GMT -8
The J valve can be a useful tool if the diver uses it properly. Just like a pressure gauge, it has to be checked during the dive. I have bumped a rod or two and pushed them back up. Once I was into my reserve when I checked it, and had to ascend right away.
I was a street cop for 24 years and learned that my pistol was in the same place at all times. I also carried the same pistol at all times (Colt .45 1911A1) When I got scared on or off duty, my hand went to my right hip and there were no surprizes. I would suggest that the J be left in the same place and a banjo fitting be added with a pressure gauge. Surprizes are not good things for cops or divers.
The reason divers on Flipper and Mike Nelson had their lead on under their harnesses and the J rod down, was there was a rack of tanks just off camera. They would just swim a few yards and change tanks whenever air got low. They were in about 20 feet of water too, with lots of help nearby. They were not trying to set safety standards for anyone, just make a film.
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Creed
Pro Diver
Posts: 189
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Post by Creed on Oct 10, 2006 7:39:34 GMT -8
I've pretty much moved to Sherwood manifolds for my doubles. I like the flexibility of configuration. I was inspired by the tanks Searat and Nemrod set up.
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Post by luis on Oct 10, 2006 9:23:28 GMT -8
Many (if not most) “J” valves allow you to install the lever facing backwards or forward. The reserve mechanism and lever are totally symmetrical, and the stem where the handle mounts onto is square. This allows you to remove the handle and relocating it facing forward or backwards.
The reserve work by rotating the handle 90 degrees and doesn’t care if the rotation is clockwise or counterclockwise.
WARNING: if you decide to change the reserve handle, make sure if you had it UP when you removed the handle you re-install it in the UP position (whether it is facing forward or facing back). The reserve should open when the handle is pulled down. Do not think about the handle rotation. If this is not extremely clear, DO NOT attempt to change the reserve lever.
The last thing you want is to get down to the reserve and think that you are opening when in reality you are closing it.
Having a reserve lever in the wrong position is bad new and it happened to a friend of mine. His little brother (also a diver) messed around with his reserve lever and installed it backwards by accident. We were building an artificial reef (my high school marine biology club) when my friend notified me that he was getting close to reserve (I was the safety officer at the time). When he pulled his reserve I saw his eyes and didn’t need any other signal. I don’t remember if I had an octopus back then, it didn’t mater. I swam towards him before he had a chance to give the OOA sign.
In those days doing a free ascent from around 40 ft was no issue for any of us, but he just exhaled his last breath before pulling his reserve, and we have been working fairly hard. Pulling the reserve lever actually closed any air left. The things we got away with as kids is always amazing.
Valves that I know are reversible: Scubapro, Old Sherwood and all the valves made by Sherwood: Healthways, Dacor, etc… etc.
I am fairly certain USD valves are also reversible. I haven’t tried it with the newer Sherwood, but would be surprised if they are not reversible.
The only valve I know for sure is not reversible is the old Sportsways valves. The stem was rectangular so the handle only fits one way.
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Post by nemrod on Oct 10, 2006 9:34:29 GMT -8
When I first got back into traditional diving I had recalled similar methods of setting up tanks, valves and doubles. I think I posted my questions here and SeaRat answered that it was the Sherwood manifold that I was thinking of. While it is modular, which is often detrimental with vavles it does not seem prone to leakage and one can do all sorts of tricks with it, flipping posts, adding posts, flipping J valves and on and on. The one thing it does not do that a modern manifold can do is isolate one tank from another. It can isolate the regulators but not the tanks. If tank isolation--total redundancy is needed---rare outside of cave diving and deep wreck/tech stuff----then it is probably not a good manifold to build on, in that case singles rigged in double bands are probably better or a modern isolation manifold, which of course works poorely or not at all with a double hose.
I used to flip the J valves and not use a rod, I would just grab the bottom of the tank and lift it up so I could reach to the valve. Most of the time I run an spg on a banjo or on the single hose if diving a Sherwood manifolded double set up. The J valve is either set down or removed. I don't like the way some of my J valves make my spg needles rise and fall with each breath, cannot be good for them.
I reverse the Dacor valves, they are a good valve and work with a banjo well also. Yes, Luis is right, you can install them backwards,i wonder how I would know that?
James
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Post by SeaRat on Oct 10, 2006 9:38:55 GMT -8
I would like to make a couple of points here. With a double manifold J-valve, there is no need to reverse the J-valve as it is sitting on the valve. What we are doing is exchanging positions, and also reversing the center section of the manifold, so that the right cylinder becomes the reserve cylinder. In doing this, the reserve valve itself is not touched, and remains the same as it was from the factory. It is simply a configuration change on the double cylinders.
What we are talking about in changing the resevere valve itself applies only to a single cylinder valve (one ment to go on a single cylinder). I know that the Scubapro valve was designed to do this (see above). But I do not know whether any of the other valves can be reversed, and even though I respect Luis, I would need to look at some of my valves (I'm at work right now) to see. But even if this can be done, I would highly recommend that you follow the following procedure, that I got from a cut sheet on installing the J-reserve valve module from AMF Voit (I'll try to post that sheet later):
--After you have made the change, fill the cylinder up to 600 or so psig (for a 300-350 psi reserve valve spring). --Place the valve in the "Up" position (reserve on), and begin letting the air out. The air should stop flowing at the spring setting (300 or 350 psig). --Then trip the J-valve's reserve lever, and the air should again flow. If it does not, you have the lever in the wrong position.
It is important that you make this performance test to ensure that the valve is functioning properly. Not to do this is to simply trust your luck, and perhaps have to cope with the type of situation Luis described above.
John
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Post by SeaRat on Oct 10, 2006 12:04:10 GMT -8
I have looked at my J-valves (its noon time), and neither my USD J-valve (plastic knob and lever) and my AMF Voit J-valve can be mounted backwards. They have indentations in the lever or body (or both) that preclude this. These valves can still be mounted with the lever wrong. I have an aluminum valve based upon the AMF Voit design, but without Voit (or other) name on it, which can be reversed, and my Sherwood Low Profile J Valve (Model SVB 1395 A) can also be reversed. I also have scanned the Voit Installation Instructions for the VI-JR assembly in the K-valve assembly. This has the checking procedure, so use this instead of what I wrote above: Good luck, John
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Post by treasureman on Nov 24, 2006 15:34:33 GMT -8
I have a USD solid bar manifold with rubber knobs it is a J. I use it on twin 50 and I could have sworn that I breathed past the reserve without it ever having tripped. Anyone out there service these... forget the local dive shop here, they say they wont touch it cause its so old
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Post by SeaRat on Nov 24, 2006 21:51:54 GMT -8
Treasureman,
You can use the procedure that AMF Voit printed above, but on your tanks, to check the functioning of the J valve. Have the LDS fill the tanks to about 800-1000 psi, then make sure the reserve lever is in the "up" or "dive" position. Let the air out of the tanks, using the main valve or the purge button on a single hose regulator. Once the air flowed has slowed almost to a stop, trip the reserve and see if you get more flow, or if you have the single hose regulator on it you should get a cross-feeding of the air into the other (drained) tank. If there is a gauge on the regulator, it will go from zero psi (gauge) to about 250 psi (gauge), as the spring on twin manifolds is almost universally set at 500 psi. But that 500 psi is only in one tank, and it will cross-feed into the other one, and equilize at 250 psi.
If you don't get that flow, then the reserve is in the wrong position or is not working for some reason. Usually its because the lever was mounted in the wrong position, so that "up" is the "reserve" position and down is the "dive" position (using the Voit nominclature above). If the lever works, but oppositely, you can keep it there and just know that you need to have in in the "down" position to dive, and push it up for the "reserve" function to work.
If you do get flow, then quickly put the lever back up to block the flow again. Remember that it will still flow out of the other tank--let it drain, then move the lever down just slightly until you again activate the reserve (it will be below 250 psi now). This will tell you how easy it is to trip the valve, and that you may need to check it throughout the dive (a good idea anyway).
There is one other thing that may have happened, and that is that you have a functioning valve, but don't realize that it is for only one cylinder. You can breath the other cylinder down to zero psi (gauge) and still have your reserve. If this is happening, simply let it go to zero on the gauge, then trip the reserve and it should jump back up to 250 psi.
Normally divers now don't dive their tanks down that low, and so the final thought here is that, if you are using a gauge, you may be coming out of the water with more than 500 psi in the tanks. The J reserve doesn't kick in until you are below 500 psi, and that only happens in one tank, so you won't be aware of it until your gauge reads zero.
'Hope this helps.
John
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Post by duckbill on Nov 25, 2006 1:38:09 GMT -8
A quick addition. 1) Do as John said, but after you drain the one side completely, close the main valve and let the J-valve stay where it is for, say, half an hour. Then re-open the main valve and see if you get any more air coming out of your "empty" tank (all this BEFORE tripping the J-valve). If you do get additional pressure coming out, but the J-valve otherwise functions correctly, then you have a slow leak in the J. That happened to me this last season. The J-valve was slowly cross-bleeding more than it was designed to while I was diving and breathing off of it, so when I went to trip it there was only about 180 psi of reserve pressure!!!!! One more aside related to the above just to confuse things- The J actually "kicks in" (closes) immediately when it is turned up after a fill, because both tanks are at equal pressure. After the first 500 psi are used from the non-J-valved tank, the J-valve opens slightly at each breath during the rest of the dive to bleed air across and maintain a 500 psi differential (i.e. 500 psi more in the J-valved tank than in the non-J-valved tank for any given pressure). Then, nearing the end when the non-J tank is breathed down, you now have that additional 500 psi to use (equalizing to 250 psi when tripped, as John said). Personally, I like a larger reserve on small doubles. As an example, here would be some non-J / J-valved pressures throughout a dive. I hope this helps to clarify what I might have missed: 1800/1800 (start of the dive) 1700/1800 1600/1800 1500/1800 1400/1800 1300/1800 (500 psi differential reached- J bleeds to maintain it from here on out) 1200/1700 1100/1600 1000/1500 900/1400 800/1300 700/1200 600/1100 500/1000 400/900 300/800 200/700 100/600 (breathing starts to become restricted) 0/500 -J-valve tripped- 250/250 (take one last photograph) 150/150 (get your bearings and start heading toward shore) 50/50 (getting hard to breathe) 0/0 (surface! )
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Post by william on Nov 25, 2006 16:21:42 GMT -8
That is just Great Duckbill. Even a D-A like me can understand some, ha, ha. Thank you for going to the trouble and Careing enough to try and explain this.
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Post by william on Nov 25, 2006 16:23:32 GMT -8
I WAS MEANING TO HAVE JOHN'S NAME THERE TOO BUT HIT THE POST REPLY BUTTOM TOO FAST THANK YOU TOO JOHN
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Post by JES on Nov 25, 2006 16:39:12 GMT -8
I WAS MEANING TO HAVE JOHN'S NAME THERE TOO BUT HIT THE POST REPLY BUTTON TOO FAST THANK YOU TOO JOHN William, Don't forget that you can modify/correct your posts by clicking the modify[/i] button in the upper right-hand corner of your original post. This will save you from needing to make a new post in order to correct a previous reply.
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