J -valve

Can someone please tell me what a J valve is, cheers?

A J valve has a built in reserve.

Your standard valve on your tank is a K valve, standard off on valve.

The J valve has off on and reserve. (Pre Presure gage). The idea
was you put the valve on and at about 50 bar it got hard to breath
and you switched it to reserve and surfaced.

On Mon, 8 Sep 2003 23:21:01 +0100, "Mark"
<mark@moat99.freeserve.co.uk> wrote:

>Can someone please tell me what a J valve is, cheers?
>

"Mark" <mark@moat99.freeserve.co.uk> wrote in message news:<bjivch$1vi$1@news8.svr.pol.co.uk>...
> Can someone please tell me what a J valve is, cheers?

Cylinder valve with a built in 'reserve'. A spring shuts the air off
at a pre-set pressure (used to be about 30 bar IIRC), the diver pulls
the handle to release the spring and get access to the 'reserve'.

Mick

In article <bjivch$1vi$1@news8.svr.pol.co.uk>,
Mark <mark@moat99.freeserve.co.uk> wrote:
>Can someone please tell me what a J valve is, cheers?

As I understand it, it was catalogue code "J" in the original Scubapro
catalogue. The next item was item "K" which was similar, but didn't have
the "reserve" pull mechanism.

Gordon

Top posting is bad.
http://www.dickalba.demon.co.uk/usen.../faq_topp.html

Mark,

Have a look on some tank boots and you will see a small bit slicking out
with a hole in it, this is hole for metal pull lever which roates the
reserve mechanism on the J valve.

This happens at about 50 bar - hence the stupid reliance on 50 bar as a
reserve when sometime 20 is enough and other times 100 is more sensible.

The valve are still in use (quite a few ols french sea dogs !) .

They are a bit like the isolator on a manifold - they can cause problems by
being there, espcially if entering the water with them in the wrong state or
filling with them in the wrong state.

I think the HSE used to accept them in the UK as an acceptable source of
reserve gas, but that may be hearsay.

If Gi III invented it, we would all be using it.

Tony
"Mark" <mark@moat99.freeserve.co.uk> wrote in message
news:bjivch$1vi$1@news8.svr.pol.co.uk...
> Can someone please tell me what a J valve is, cheers?
>
>

Thank you everyone for your help, Mark
"Tony Jay" <Tony.Jay@nospam.bsac.com> wrote in message
news:vlrddnpmf3hebb@corp.supernews.com...
> Mark,
>
> Have a look on some tank boots and you will see a small bit slicking out
> with a hole in it, this is hole for metal pull lever which roates the
> reserve mechanism on the J valve.
>
> This happens at about 50 bar - hence the stupid reliance on 50 bar as a
> reserve when sometime 20 is enough and other times 100 is more sensible.
>
> The valve are still in use (quite a few ols french sea dogs !) .
>
> They are a bit like the isolator on a manifold - they can cause problems
by
> being there, espcially if entering the water with them in the wrong state
or
> filling with them in the wrong state.
>
> I think the HSE used to accept them in the UK as an acceptable source of
> reserve gas, but that may be hearsay.
>
> If Gi III invented it, we would all be using it.
>
> Tony
> "Mark" <mark@moat99.freeserve.co.uk> wrote in message
> news:bjivch$1vi$1@news8.svr.pol.co.uk...
> > Can someone please tell me what a J valve is, cheers?
> >
> >
>
>

On Tue, 9 Sep 2003 12:12:54 +0100, "Tony Jay"
<Tony.Jay@nospam.bsac.com> wrote:
snip
>I think the HSE used to accept them in the UK as an acceptable source of
>reserve gas, but that may be hearsay.
>

Yes they used to, but not any more.

--
Steve Barlow