Need help disassembling J-valve

[rx7diver]

Can you post a link to that manual?

Thanks

PDF is Attached.

Interesting: The two schematics (for the single J-valve and the single-outlet double-tank manifold J-valve, resp.) indicate the same part number (#052508) for the "Reserve Assembly." I just tested mine again. It closes off somewhere between 200 and 250 psig. Call it 225 psig.

There is a screw/bolt that passes through the center of the Reserve Assembly, through its spring. I am wondering if I can screw down the Assembly to increase its spring pressure (i.e., its "actuation pressure"). If so, then maybe mine was set originally for the manifold and never adjusted for the single valve.

Hmmm. Stay tuned...

rx7diver

 

[Luis H]

I don't believe the screw will make any difference. They were not adjustable.

The spring pushes the seat against the orifice in the body and I think it is the "bonnet" (item 22 in both diagrams) that pushes the assembly in. Notice all the part number are the same, except for the bonnets. It may be that the bonnet length is what controls how much the assembly is pushed (but I would have to look at one again).

The last time I serviced one of these valves was about 45 years ago.

I do have a couple of them, but I don't use them.

Good luck.


Thanks for the manual.

 

[captain]

You will find it here along with a lot of others. It seem t has to be requested now, it was available directly. I think it might be in Vintage Double Hose manuals.

https://aqualung.com/militaryandprofessional/techlib.shtml

 

[captain]

Keep in mind the J valve is not an on one second and off the next operation. It starts to restrict flow before it shuts off and it may not ever shut off completely. A better test is to determine at what pressure it starts restricting inhalation.

 

[Luis H]

Keep in mind the J valve is not an on one second and off the next operation. It starts to restrict flow before it shuts off and it may not ever shut off completely. A better test is to determine at what pressure it starts restricting inhalation.

That is exactly how I remember a lot of J-valves, but when I tried to explain that, some other divers keep on thinking that it is a malfunction and it need to be fixed.

Thanks

 

[rx7diver]

Keep in mind the J valve is not an on one second and off the next operation. It starts to restrict flow before it shuts off and it may not ever shut off completely. A better test is to determine at what pressure it starts restricting inhalation.

Yes, this was one of my surprises when I began testing mine: When breathing down the cylinder, as you get nearer the "actuation pressure", inhaling becomes progressively harder. You can definitely tell you're getting close, though. Finally, pulling the J-rod is like inhaling a breath of fresh air! (See what I did there!!??)

I imagine that if you were breathing while swimming at depth at a moderate rate using a flutter kick (say), you would notice the increasing breathing resistance much sooner.

You know, a couple of 72's we used in my univ scuba course (in 1986) wore J-valves sans pull-rods. We used these whenever we were running low on full 72's wearing K-valves. We were always careful to use them with the switch in the "down" position, though, so I never experienced the cut-off back then.

(Of course, the couple of us TA's who were allowed to run the compressor and fill cylinders knew to fill them with the J-valve switch in the "down" position.)

rx7diver