J valves or so I think?

[Doghouse]

I was diving a gentleman's boat today, and he said the he used to dive and would like to give me some stuff. So heck like I am going to say no...

Well he brought up 3 tank valves. 2 singles, and 1 double.

Now being still a little young in diving, I thought these were a little wierd as there is a switch on one side. I presume that these are J-valves, am I correct?

Are they still worth using?

Thanks for the input.

[Splitlip]

They are j valves if the switch is a lever on the other side of the valve from the knob. It will have a hole in the lever.

Worth diving? Maybe. If you are using an SPG, make sure the lever is down.

[texdiveguy]

Originally Posted by Doghouse

I was diving a gentleman's boat today, and he said the he used to dive and would like to give me some stuff. So heck like I am going to say no...

Well he brought up 3 tank valves. 2 singles, and 1 double.

Now being still a little young in diving, I thought these were a little wierd as there is a switch on one side. I presume that these are J-valves, am I correct?

Are they still worth using?

Thanks for the input.

They are a J-valve, you are correct!!

The modern K valves are better now--I would use one of those myself...but you can 'disarm' the reserve portion of the old J's and use them assuming they are in working order and rebuilt inside......vintage gear divers like them as is and will rebuild them to use with their vintage set-ups. I started diving on J valves in the early 70's....oh the days--lol!

[reactive]

Yeah, that sounds like a J-valve. I know a guy that still uses his, but there are several precautions you need to take when using them. You need to make sure the valve switch is in the correct position BEFORE you get in the water with it, and you need to make sure it's in the proper position when filling the tank. Also, you want to make sure you don't bump it while diving so it doesn't switch positions. As long as you rely on your pressure gauges and not the reserve switch, you should be fine though.

[Doghouse]

Thanks for the pic, so yup, I have 3 j valves.

I was thinking about getting a doubles setup, and this may be the trick.

[Crimediver]

The two in the picture are Dacor J-valves. They are built to be bulletproof and are solid brass. There is a HP port on those valves that a SPG hose can be screwed into for monitoring air supply. They were popular back in the day when many regs had no HP port. I use them in vintage diving with a Voit double hose reg.

You will need to see if the valve threads are 3/4" o-ring sealed thread or 1/2" tapered pipe threads. The double manifold will be easier to use if it is 3/4" or you will need to score some old steel 72 tanks with a 1/2" neck.
A vintage diver would use them but most divers or LDS will tell you you need a manifold with an isolation valve, etc. If they are 1/2" you will need steel 72 which would require you to find a set of bands to fit it. The diameter would be 6.9 inches. The tanks will also be lower pressure tanks like 2250 psi or so. If you are interested in setting up doubles PM me and I can steer you to some vintage dive suppliers than can assist you. The j-valves had a rod attached to the lever that a diver would pull to activate the reserve.
FWIW the j-valve is not obsolete and is currently used by the US Navy and may be mandated by OSHA in certain diving applications. It is still currently manufactured and is a LOT more expensive than a K-valve.

[Doghouse]

I will take some pic's of what I have and post them up here. They all have o-rings so I would guess that they are not the 1/2.

[captain]

There is aboutely nothing dangerous about using J valves if you understand how they work.
With the lever in the up position the valve will automaticly hold back between 300psi (single tank) and 500 psi (double manifold) in reserve. When the lever is turned down it releases the last 300 or 500 psi. You can leave the lever down at all times and use it just as a K valve.
Or you can start the dive with the lever up. If you get down to 300 or 500 psi it will become harder to suck air and also yor SPG will begin to drop with every inhalation. Flip the lever and down the last 300 or 500 psi will be available. Considering most diver don't breathe a tank down to less than 500 psi it will never come into play.
Also the lever must be in the down position in order to fill the tank. If the J lever is up in the case of a double manifold only the tank on the side without the J lever will be filled and the tank on the side with the J lever will not fill.
I have J valves on all of my tanks. They were developed before the SPG was invented and also for low or no vis conditions when an SPG can't be read.
When left in the up position it can also serve as a warning to a diver that is distracted and doesn't watch his SPG closely.

[Doghouse]

here is a picture of the valves.
1: with yellow cap US.Divers CO Santa Ana CAL on teh neck is UB the back is stamped CB. Above the CB is a nut with t50 stamped in it.
2:same as above but CB is stamped on the back

3: again US.Divers CO Los Angeles CAL J62-1 iz and J62-3 FY. on the tank valves. The center has 1A stamped on it.

Are these worth anything?

[captain]

Very little to go wrong with a valve. If they operate easily and don't leak they should be fine. No need to get them serviced unless there is a reason and just being old is not reason enough. I have 50 year old valves that have all original parts in them. The double manifold would be great for a pair of AL 50's. Or put them on ebay.