J-Valve reserve plug?

[alpegmusic]

If you use those valves, you really need to replace those burst discs. If I remember correctly from my PSI/PCI class, the word “illegal” was used. And that is because they are fairly dangerous if/when they fail due to pressure being released in a single direction. Modern burst discs direct the air in 3 opposing/cancelling directions, imparting minimal motion to the cylinder.

I would expect a high likelihood that any shop paying attention will not fill a cylinder with such a valve. The hazard is more on them at time of fill than on you.

Yes, when my 1970-ish USD cylinder was refilled in 2009 after a 30 year hiatus and successful hydro, the old single direction burst disk blew and caused the cylinder to dance around the room, knocking a hole in the plaster. Fortunately, the corroded disk blew at a fairly low pressure. Tom Huff, the shop owner, kindly replaced the valve with a rebuilt Genesis K-valve at no cost (thereby winning a loyal customer for many years).

 

[ScubaBunga]

Yeah I have several bust disk kits, that’s not an issue. I had heard of plugs for the reserve lever and if I can find them it just simplifies the valves to basically k-valves. Most of my tanks are steel 72’s, so I had to some searching to find the 2250 burst disks. In the end it was my LDS that came through on having those. They may have some plugs too but he was out with some medical issues, so I haven’t talked to him in a while.

 

[Bowers]

i ziptie my valve down, but i imagine (never tried it), that you could take it apart and remove the spring or grind the lever even, so that in either position the valve will not be in "reserve".

 

[John C. Ratliff]

i ziptie my valve down, but i imagine (never tried it), that you could take it apart and remove the spring or grind the lever even, so that in either position the valve will not be in "reserve".

Or, will always be on, and impossible to fill. Not a good idea, in my opinion.

SeaRat

PS, I have no idea why this prejudice against a very good valve design. And if you don't like it, simply leave it in the "down," or "Off" position.

 

[ScubaBunga]

I don’t mind them and have them on other tanks, but since I never use the reserve lever, if there is a simple plug, then next time I service them it’s one less moving part. If I can’t find plugs these valves will still be in service, they are actually easier to carry than my old oms k-valves. They would be even easier with a plug instead of the lever!

 

[Bowers]

Or, will always be on, and impossible to fill. Not a good idea, in my opinion.

SeaRat

PS, I have no idea why this prejudice against a very good valve design. And if you don't like it, simply leave it in the "down," or "Off" position.

my understanding is that the spring tension is what overcomes the pressure in the tank and closes the valve at about 500 psi. so wouldnt removing the spring make it a one seated valve that would act as a kvalve regardless of whether the lever is up or down? how would having it in the open (down) position make it impossible to fill since its supposed to be filled in the open position anyway? im not being argumentative, i legitimately want to understand.

 

[John C. Ratliff]

my understanding is that the spring tension is what overcomes the pressure in the tank and closes the valve at about 500 psi. so wouldnt removing the spring make it a one seated valve that would act as a kvalve regardless of whether the lever is up or down? how would having it in the open (down) position make it impossible to fill since its supposed to be filled in the open position anyway? im not being argumentative, i legitimately want to understand.

Bowers,

It really depends on the specific J-valve design. Without a schematic of your specific J-valve, you may think you are removing the active spring, and actually there is another spring on the other side of the valve which closes the valve, usually at 300 psig on single tanks, 500 psig on one side of a doubles manifold. Before messing with the valve, be sure you know what you are doing. I'll see if I can find some schematics to illustrate this.

Concerning the filling, if it is inadvertently left in the "Up" position, with the seat's stem ground off, you won't be able to fill the tank. Some valve designs depend upon the reserve spring to make a seal too on the other side, the outside, so it must be left in to hold air, which sets up the potential for the wrong position.

SeaRat

 

[John C. Ratliff]

Here's a Scubapro J-valve, with the spring in the top of the valve. (more later)

SeaRat