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A slow SPG is a bad thing?

Discussion in 'Basic Scuba Discussions' started by Nathan Doty, Oct 13, 2019.

  1. Nathan Doty

    Nathan Doty Barracuda

    Short story, I picked up a used spg, hooked it up to a tank and instead of quickly snapping to pressure it took 10-12 seconds to get there. It did match my other gauge, eventually. So even though it does 'work' I think it would be a bad idea to use it as it won't react quickly enough to show some of the troubleshooting things we do. Am I correct in thinking this way?

    I pulled it out of the boot and corrosion city. I've had it soaking in vinegar over night and hopefully it will start working correctly. If not I'll dig up some old parts and rig it up as a pressure checker to use instead of breaking out my reg set every time.
  2. divad

    divad Solo Diver

    Maybe the tiny hole in the spool got gunked-up somehow? Put it in a bucket of water and pressurize it, so you can check for bubbles.
  3. davehicks

    davehicks Barracuda

    # of Dives: 1,000 - 2,499
    Location: Seattle
    Don't dive with this SPG until it's repaired or replaced.

    You can change the spool ($3 part) that makes the swivel connection between the hose and gauge which is worth a try. If that does not do it then the gauge likely has water/salt intrusion. I don't know if that is worth trying to fix, just by a new one.
    DogDiver, Khrissi and JamesBon92007 like this.
  4. broncobowsher

    broncobowsher Solo Diver

    Not good. Not only does it tell you the pressure in the tank, but it can give warnings of other issues. Tank valve not completely open, or open at all? the SPG will dip on an inhale. A slow gauge won't show that. Worse is if the partial clog becomes a full clog and you breath the tank down but the gauge still shows you have air left.

    Something else to check, the hose itself. if the gauge doesn't respond correctly on a different hose/spool, toss it.
  5. Nathan Doty

    Nathan Doty Barracuda

    Success! Soaked and cleaned, blown out with air and it's working as well as my other 2. So its either fixed or I've got 3 bad ones....
    happy-diver, couv, flyboy08 and 5 others like this.
  6. hsinhai

    hsinhai Nassau Grouper

    # of Dives: 200 - 499
    Location: Taipei, Taiwan
    Noticed a slow needle, fortunately brought a spare SPG with me the following weekend.. lucky as it had totally seized..

    If the SPG had gunk in the bourdon tube, best replace it. It may indicate poorly stored prior to use, water in rental tanks or water ingress while soaking regs.
  7. Neilwood

    Neilwood Loggerhead Turtle

    # of Dives: 50 - 99
    Location: Scotland
    Personally I would not trust an SPG that I have found to be faulty. If it has stuck in the past, there is a good chance it might stick in the future.

    Slow is probably one of the worst ways to go. It affects your ability to check for proper function when doing a breath check. Also in use can you be sure that it is slow or stuck?
  8. divad

    divad Solo Diver


    All he did was blow out the spool....its impossible to blow out the bourdon tube. I would have just put in a new spool, but, what works...works.
    Dark Wolf and Bob DBF like this.
  9. wedivebc

    wedivebc CCR Instructor ScubaBoard Supporter

    A slow reacting SPG is symptomatic of water infiltration through the orfice which is likely already into the bourdon tube. I would toss it and get a new. I was diving with a guy who ran out of air because his needle stuck at 1000psi or so.
    rjack321 likes this.
  10. divad

    divad Solo Diver

    Its no longer slow-reacting according to the OP.

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