J valves - question

[pt40fathoms]

What an excelent descripton of the operation of these valves.
The only thing you left out were the stats on the number of apparent diver/drowning that occurred when a diver would attempt to activate the remaining air pressure, only to discover that sometime during the dive it was, and the reserve is already
used up.
This being the reason the "gas gauge" SPG was so important in making diving a safe sport.

J-valves,Save em for display in a case,but don't put them in with your diving gear anymore than you would include a BCD with an inflater stuck open.
they have far too much of a chance for failure.Use a SPG,plan your dive,dive your plan

Brian

What an alarmist reaction.

The only time someone uses a J-Valve in it's original intended configuration, is during a dive with "vintage" equipment. The rest of the time, the diver would have an SPG and dive the tank like any other. There is nothing mechanically wrong, and nothing dangerous about, diving with a tank fitted with a J-Valve. Equating it to diving with a piece of gear that is defective is just plain silly.

 

[CIBDiving]

As has been said it was before SPGs. Yes, you had to fill with the reserve open to get air into the tank, You also had be sure to return the valve to the "up" position Before you dove or you got a nasty suprise when you went to use the reserve. There was also the problem of the accuating rod getting pulled by accident without your knowlege. Some reckless few would challenge darwin by pulling the reserve and continuing the dive rather than starting up. There is no real reason to not use these valves, the things were/are pretty bullet proof.

 

[miketsp]

..snip..
The only time someone uses a J-Valve in it's original intended configuration, is during a dive with "vintage" equipment.
..snip..

Not true. Until somebody invents a way of reading an SPG in zero vis there is no substitute for a J-valve. I know divers that depend on them for daily work diving.

 

[dpbishop]

There were a number of safety devices on the market before ( and after) the spg became standard. Scubapro had a regulator that would honk like a goose in heat when it hit 500 psi. It startled the heck out of me the first time I borrowed one; but it was hard to ignore. I've noticed when I'm lobster diving I don't need a spg, I now I've hit 500 when I find the big reef where all the lobster hang out. Happens every time.

 

[SStrecker]

When I started diving, back in 1974, the J-Valve was the only option but everyone I knew also had SPGs. They seemed like a good idea at the time but valve position caution was always necessary. I dropped out of the sport in 1981. Imagine my surprise to see them relegated to the historical legacy of Sea Hunt era gear, when I returned to the sport, last year. In all fairness, I miss the J-Valve but we are better off without it.

 

[spectrum]

I've only had J valves in the pool but they were no big deal. I would dive them anytime with contemporary gauges if the need came up. I suppose I could start the dive with the reserve open and manage the dive like it was a K valve of use the reserve for the nostalgia of it all.As long as you use modern gas management technique (not assuming the reserve is there) you're all set since it's a failsafe condition.

Now before the SPG the only other option would be to understand your time, depth and personal air consumption on that dive. Hopefully the human computer would turn the dive in time. The final warniing would be breathing resistance but that may be a very late warning depending on regulator in use. I understand that some double hose units actually do breathe easier as the cylinder pressure drops so that is a very subtle cue.

So in the vintage world of dive management the SPG was not in use but when did the depth gauge come into common use? I find depth to be nearly impossible to guess at other than knowing the site. Knowing the depth would be critical in mental gas management. Hence the J valve reserve and the careful monitoring of that activating rod.

Pete

 

[Wayward Son]

So in the vintage world of dive management the SPG was not in use but when did the depth gauge come into common use?

During the 1970's. When I started in the early 70's, SPG's were around but still considered optional. Some divers I knew had them, the ones that couldn't afford them did not. Me, for example. The J valve was the std valve still.

I left Turkey late in 1975 when my dad retired from the Air Force. In spring of 1978 I finally took a class & got legally certified. I had taken & passed OW 3 times already, but was too young to get a card

Anyway, by that time the SPG was std equipment. Octopus 2nd stages were still considered a costly option that most didn't have. Me, for example, and the rental rigs used by the class did not have them. The class taught buddy breathing, not handing off an extra stage. It also taught the use of a BC, something I had never seen before. The K valve was now the std valve, though J's were still quite common. In fact, I bought a steel 72 then & got it with a J (still have & use the tank & valve).

Now, octo's are std (required to take the local PADI class), & buddy breathing is not taught, mostly. Dive computers are in wide use, to the point that at least one agency no longer teaches how to use a table.

 

[agilis]

I have a US Divers wrist mount oil filled depth gauge I've owned since 1965. I got it from a friend, and I think it dates from the late 1950s. It was made in France, and is oil-filled, brass, and seemed to works fine a couple of years ago, when I took it for an inlet dive using my original 1960s Scubapro Mark 3 regulator. These items are heavy with nostalgia, and spend most of their time carefully tucked away in my old wooden dive box. I think these oil-filled depth gauges pre-date scuba by many years, and were used by commercial and navy divers before WW2.

I still have an old Voit steel 72 with a lovely Dacor J-valve. The valve is chrome-plated brass, including the heavily knurled valve opening wheel. No plastic. I don't use this rig, but I do keep some air pressure in the tank. Also in the old dive box with miscellaneous masks, fins, etc., is a perfect, like-new Dacor dive knife that I found in Negril, Jamaica in the mid-70s, shortly after Dacor completed a dive catalog photo shoot off Negril's then-pristine cliffs. One of the models probably dropped it.

The knife looks as good as it did 30 years ago. I wish I could say as much.

 

[jrv]

the navy still uses j valves quite regularly

 

[The Chairman]

Those were the days my friend... I thought they'd never end!

How I remember the "pucker" that was the result of yanking down on the rod to find that the reserve had been open the whole time! The brief nanosecond of cerebral delay until the message hit your fins and you started your RAPID ascent. The constant working of the reg on the way up to see if there was still a teeny tiny breath that might save you, all the while pulling down on that rod a hundred times, hoping that the valve was sticky and that precious air was only a click away. Feeling the bright sun on your face as you spit your regulator out and let your aching lungs fill with sticky sweet air: FRESH AIR AND ALL I WANTED!

Oh yeah, I miss those days: NOT!

As for the use of J-Valves, I remove the inner spring and the "block" and reassemble the valve so it doesn't leak. Works fine, and you don't have to worry about showing up to a dive with an empty tank.

BTW, My Voit regulator made a funny noise at low PSI and the last breath or two was a bit labored. Of course, there were LOTS of conditions that could make it breathe hard, so I didn't always pick up on that. You can't miss the pucker though. What a rush!