J Valve

[CuriousRambler]

perhaps but I would think using surface supplied air would be a much safer bet if doing true zero visibility diving.

I don't disagree at all, but if I were playing devil's advocate, I can easily imagine a scenario where a diver might be stuck diving far enough away from vehicle access that hauling tanks to the water is enough headache, much less a compressor. Or small town nowhere, where there's simply no budget for equipment, and Old Bill is volunteering, using his personal equipment.

I think there are certainly *better* options, but they may not always be available.

Though if a new J valve is really $500, I imagine there's better ways to spend that money on safety haha

 

[2Bobbyo]

Well, I have a US Divers aluminum tank with a J valve. Date of manufacture is 1975 with numerous hydro dates. I know the tank won't be used anymore but the J valve looks new and works well. With a maintenance check, could it be used on a new tank? Do any BCDs have a slot for the pull rod?

 

[James79]

Well, I have a US Divers aluminum tank with a J valve. Date of manufacture is 1975 with numerous hydro dates. I know the tank won't be used anymore but the J valve looks new and works well. With a maintenance check, could it be used on a new tank? Do any BCDs have a slot for the pull rod?

I haven't seen slots for pull rods on any recent gear, but I've seen L brackets that you can slide under the cam band to serve as a J rod guide. I 3d printed one, works well.
Respectfully
James

 

[John C. Ratliff]

I'm not sure if everyone is aware that Cousteau and Gagnan anticipated the need for a reserve, and designed it into their three-tank system in their original patent:

Fig. 11 is a front view of said part.

Referring to Figs. 1, 2 and 3, A and B are two cylinders containing compressed air but which might as well be filled with any other compressed breathable gas. On the cylinder A is mounted a cock J through which the compressed air is ad mitted to the two cylinders for the purpose of filling them. The air inhaied by the diver is withdrawn from the cylinders through a common pipe N. A third cylinder C serves as a reserve; the gas contained in it being available for the diver when he feels that the supply of gas contained in the two cylinders A and B is close to being eihausted. The capacity of this third cylinder is sufliciently large to, supply sufllcient air to the diver to enable him to rise to the surface sufficiently slowly. The diver can thus dispense with any instruments for measuring the pressure in the two cylinders A and B. The air is withdrawn from the reserve cylinder C through a pipe 0. Pipes N and 0 are provided with cocks 'K and L, respectively, which are operated by the diver. While two cylinders A and B have been shown for the normal supply of air to the diver, only one could be utilized instead.
US2485039A - Diving unit - Google Patents

The J-valve came just a bit later. JYC apparently did not like the concept of needing to watch a gauge and monitor the air supply. Thus they elected an unmistakable reserve system, the third tank with the reserve air.

U.S. Divers Company came out with the J-Valve when they started manufacturing in the USA, probably in the early 1950s. The first USD triple tank system apparently had no reserve (silver tanks below, unlike the first Cousteau triple tanks (yellow tanks below). That was the standard for decades. It was set at 300 psig for single tanks, and 500 psig for doubles. Many of us reversed the tank positions in order is make it much, much more difficult to inadvertenrptly trip the J-valve. The UDS-1 was a triple tank system with a 759 psig J-valve reserve.

SeaRat

 

[Angelo Farina]

Well, I have a US Divers aluminum tank with a J valve. Date of manufacture is 1975 with numerous hydro dates. I know the tank won't be used anymore but the J valve looks new and works well. With a maintenance check, could it be used on a new tank? Do any BCDs have a slot for the pull rod?

Usually the rod goes into a hook or hole in the rubber foot for the cylinder. See it on the right here:

 

[Luis H]

Usually the rod goes into a hook or hole in the rubber foot for the cylinder. See it on the right here:
View attachment 580105

That may be the usual European tank boot. We don't have that type of tank boot in the US. I have a couple of those boots for my European Poseidon tanks, but I have actually never seen one with the hook.

Thanks for sharing.

 

[Luis H]

I've never used a J valve, but one thing mentioned in another thread recently is zero vis diving. I don't know what other solutions might exist, but a J valve might be just the ticket for a public safety dive in a no-vis reservoir or the like.

The Navy and OSHA both require reserve valves for zero/ low visibility work dives. Even with surface supplied air in zero visibility dives it is required to have a bail out cylinder (normally a small cylinder). The bailout cylinder is the reserve in this situation.



As an alternate to a reserve valve, a better solution is having a reserve tank. The reserve tank can have an isolation valve and it is only open when the main supply is low hand hard to breath. By decanting only when air is hard to breath, and closing the valve to the reserve after balancing the pressures, it is possible to keep track of the amount of air left.

Even that this is a better solution (and acceptable by the Navy and OSHA) it is rarely used.

This was the system used by Cousteau divers that is shown in one of John's pictures above.

 

[Luis H]

Well, I have a US Divers aluminum tank with a J valve. Date of manufacture is 1975 with numerous hydro dates. I know the tank won't be used anymore but the J valve looks new and works well. With a maintenance check, could it be used on a new tank? Do any BCDs have a slot for the pull rod?

Yes, you can use that valve on any cylinder with the same threads (3/4" NPS). You may need a new burst disc to match the working pressure of your new cylinder, but if you are staying with a 3000 psi working pressure cylinder you don't have to change anything. It is not a bad idea to replace the burst disc occasionally anyways.


If your tank band is the very common type with Velcro on the tail end of the strap, you can tuck the J-rod under the strap.

If you have the type of cam bands with the metal buckle you can also sometimes tuck th e J-rod under the end of the buckle.

One other very simple solution is to use a short length of small cord (like 6 inches of 1/4" cord or smaller), make a loop around the rod tuck the cord under the tank band.

The solution that James mention is another option.

 

[Luis H]

Now some trick questions, but real questions, mostly reserved (pun intended) for those that have experience with a reserve "J" valve.

What are the two most important skill you need to have when diving and relying on a reserve valve (no SPG)?

What is one of the most important pieces of gear needed when relying on the reserve air from valve? One hint on this question, it is not the J-rod. You can actually reach over your shoulder to turn on the reserve. The rod was just for convenience.


I should have added that I will let this run for a little while and see what kind of answers come out of it.

 

[Scuba Lawyer]

Now some trick but real questions mostly reserved (pond intended) for those that have experience with a reserve "J" valve.

What are the two most important skill you need to have when diving and relying on a reserve valve (no SPG)?

What is one of the most important pieces of gear needed when relying on the reserve air from valve? One hint on this question, it is not the J-rod. You can actually reach over your shoulder to turn on the reserve. The rod was just for convenience.

Ok Luis, I'll bite.

First, the "trick" in your questions is that no one should ever "rely" on their J-valve as a safety reserve. Second, the most important item of equipment is a watch and knowledge of your own air consumption rate at the planned dive depth. Oh yeah, and a surface tank checker guage to see what your starting pressure is. Close?