K valve vs J valve

Discussion in 'Tanks, Valves and Bands' started by TwoBitTxn, Nov 13, 2001.

  1. TwoBitTxn

    TwoBitTxn Scuba Instructor

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    Help please...

    A J valve is the single knob job that is most commonly seen on aluminum tanks right?

    A K valve has two knobs right?

    What do the two knobs do?

    Why the difference?

    Tom
     
  2. large_diver

    large_diver Loggerhead Turtle

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    Close -- K valve is the common "one knob" valve you see on most tanks today.

    I've never actually seen a J, but have read about them before. See link below for a pic and description.
    http://www.diverlink.com/gear/earlygear.htm
     
  3. Rick Murchison

    Rick Murchison Uncle Ricky Staff Member ScubaBoard Supporter

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    The "K" valve is the standard on/off valve commonly seen on most tanks.
    The "J" valve has a lever that when raised cuts off airflow at about 300 psi - by lowering the lever you gain access to the last 300 psi. This valve was used before the advent of the SPG as an emergency indicator it was time to end the dive.
    The "H" valve has two independently controlled orifices and will accept two first stage regulators. Many will accept both DIN and Yoke regs (via a yoke insert). HP variety are DIN only.
    The "Y" valve is like the "H" valve but older, and less common today as the "H" valve can be adapted to a manifold for doubling tanks where the "Y" valve can't.
    Rick
     
  4. NetDoc

    NetDoc Chairman of the Board

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    The "Dump Valve" used in the Warhammer Manouver... Unlike the others it HAS to be O2 cleaned for all environments... I almost forgot the Bivalve... which exist on many an ocean floor. And the Valve-salva manouver... Then there's the stuff to lube all of these valves, aka valve-oline. Does anyone still drive a Valvo??? Sorry, just got a bit over in-valved in the process...
     
  5. Ontario Diver

    Ontario Diver Loggerhead Turtle

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    Good answer Rick, just let me add a little bit.....

    Most rental "J"'s have been modified to remove the lever action and function just like a "K".

    The names come from the item numbers that were used to identify the valve in the early catalogs. (A "L" valve was item L; the "K" valve was item K, etc.)
     
  6. TexasMike

    TexasMike Loggerhead Turtle

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    Pete....

    And in one way(valve), I always keep the butterfly(valves) close to my heart(valves).


    Sorry...couldn't resist the very obvious pun(valve).
     
  7. NetDoc

    NetDoc Chairman of the Board

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    I think I o-puned a can of worms... yeah, yeah, I know I am one to puntificate... remember I valve-u our friendship, so I will be quiet now... As Vince Lombardi once said... "When in doubt, Pun!"
     
  8. TwoBitTxn

    TwoBitTxn Scuba Instructor

    # of Dives: 200 - 499
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    Ok I think I understand, but I'll try to describe what I have and get some one to explain what I got.

    I picked up a tank that has a knob on one side that is obviously the on/off. It has another knob 180* from it with the port in the middle. What do I have and what does the other knob do?

    The tank needs a hydro and is empty. So I can't fill it to find out.

    Tom
     
  9. miked

    miked Surface Interval Member

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    Tom,
    This is a semi-wild, semi-educated guess, but you might have a "J-valve" ,with function as accurately described by Rick.
    Does the knob opposite the "on /off" knob have anything that looks like an attachment point for a hook ended rod?(a small hole or "eyelet"?)If so, that would be a stronger indicator that you have a "J valve". I also remember being told that the "other" knob was there for ease of carrying- but that always sounded a little strange, as we were simultaneously being told to not carry the tank by the valve.

    OD, I hadn't heard the "catalog" source for the names of the different type valves before this. I recall being told that the J valve got its name from the shape of the rod used to activate the reserve PSI in the tank, and that the "Y valve" and "H valve" were so named because of their shape. (I must confess, I've never seen an H valve, so I can't judge the accuracy of that part of the claim.)
    In any event, its interesting how these different interpretations occur.
    Take care,
    Miked
     
  10. NetDoc

    NetDoc Chairman of the Board

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    A "J" valve. The knob (usually on top) opens the tank valve, the other lever (which only goes so far) is the "safety mechanism". That being said, if the tank hydros out, I would replace that valve with a newer "K" valve. BTW, the story about the catalogue is true for the H, K, and J valves... the Y get's it name from it's shape.
     
  11. Walter

    Walter Scuba Instructor

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    The J & K getting their names from the US Divers Catalog (1953?) is true, although I'm pretty sure the H got its name (as did the Y) from its shape.

    Sounds like you have a J valve. Does the extra knob have a tab on it? Does this knob only turn about 45 - 50°?

    I've never seen a J valve with the knob on the top, all of those I've seen were K valves.

    As long as your J valve is in good condition there's no reason to replace it.

    DSSW,

    WWW™
     
  12. TwoBitTxn

    TwoBitTxn Scuba Instructor

    # of Dives: 200 - 499
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    Thanks everyone.

    Yes the knob has a little tab on it with a hole and it doesn't turn very far. The shop where I took it to get hydro'ed confirmed it was a J valve. I really don't see any reason to replace it. It just looks different from all the other valves and it will make it easier to find in a cluster of tanks. It all looks in really good condition.

    Thanks again.

    Tom
     
  13. Ontario Diver

    Ontario Diver Loggerhead Turtle

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    Tom;

    Most of the J's that I see have been changed to Ks by having the second valve removed and plugged. Might be worthwhile to have the shop do it at some point so you don't "lose" 300 PSI while diving some day.
     
  14. NetDoc

    NetDoc Chairman of the Board

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    With OD! Thats why they always give me the heebie jeebies when I see one. All you need is some kid playing with it with out your knowledge. Walter, I have one that I took out of service and the valve is on top with the switch a lot lower and on the side.
     
  15. Walter

    Walter Scuba Instructor

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    Pete, thanks. I've never seen one, but there's lots of gear I've never seen being a relative new comer to the sport.

    DSSW,

    WWW™
     
  16. NetDoc

    NetDoc Chairman of the Board

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    Sarcasm does not become you. Should I take a picture of it for you??? I am sure that I can get hold of a digital camera to do that. It is an "AMF" valve and has a tiny little "T" on the top for the valve, and the switch is a stubby lever with a hole drilled in it about 2" or so below the valve. It came off of a steel 72, that I don't own anymore.
     
  17. Walter

    Walter Scuba Instructor

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    Pete, I was serious - no sarcasm. There is lots of gear I haven't seen. I enjoy learning about other things. I mean it - Thank you.

    DSSW,

    WWW™
     
  18. TwoBitTxn

    TwoBitTxn Scuba Instructor

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    All the valve does is cut off access to the last 300-500psi correct? I check it the same as I check to make sure my air is on and all is ok. I don't understand how replacing it would be a priority.

    Tom
     
  19. Ontario Diver

    Ontario Diver Loggerhead Turtle

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    Tom;

    The problem is that some of the older valves can stick or slide.

    The way that the J valve works is at the beginning of the dive the reserve valve is closed but it is on a spring set to about 300-500 PSI (I know PSI isn't the right measurement but it it simpler this way and I'll just pretend that every thing is perfect and it is a perfect spring set exactly at 500) so as long as there is more that 500 PSI in the tank the spring is pushed back and air flows. When the tank pressure drops below the spring threshold pressure- the spring has more power than the air pressure and it closes. As the diver, you would pull on the rod (Which you don't have on and reaching behind your back is dificult) to release the last 500 psi by opening the reserve valve.

    The problem is that your SPG will read the tank pressure quite well. It doesn't know about the 500 PSI thing. So if the reserve valve is mistakenly turned on or slips on or whatever, you'll find out only when your SPG goes from 501 to 0 in one breath. If you get the spring and valve seat/pin removed - the problem goes away.

    If the valve is old it may slip and do you know which way is opened and closed? I remeber that up was off and down was on but I wouldn't bet on my recollection.

    I hope that this helps. If I didn't make it clear enough just pop a message to me and I'll try again or I'll give you my AIM handle.

    Matt
     
  20. Walter

    Walter Scuba Instructor

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    J valves are fine as long as they are serviced and in good working order. Leave the J down and it works exactly like a K valve. I've heard of them getting knocked down when they should have been up, but never the other way around. If it were mine, I'd have it serviced, but as long as it's in good condition, I wouldn't replace it.

    DSSW,

    WWW™
     

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