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Hydro Testing + Rating

Discussion in 'Tanks, Valves and Bands' started by SVT_Tactical, Apr 24, 2015.

  1. SVT_Tactical

    SVT_Tactical Solo Diver

    # of Dives: 200 - 499
    Location: Shallotte, North Carolina
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    Anything special a shop has to do when hydro testing tanks so they can be + stamped? They were + marked when produced in 10' but don't want to loose that when they get hydro'ed.
     
  2. 1bubbleoff

    1bubbleoff Barracuda

    # of Dives: 1,000 - 2,499
    Location: Midwest
    287
    209
    43
    SVT-

    I suspect that being produced in '10..the Hydro test pressure as well as the REE should be stamped on the tank.

    RULE 1!!! ASK and make SURE the hydro facility understands you want the + rating, and have them explain to you HOW it's done. If they don't know, are unsure, or can't tell you what the term "REE" is...run. Don't walk...run away.

    Hydro shops can be a real issue when it comes to + ratings. Ask around your dive buddies who they use and WHY.

    Good Luck


    Bubs
     
    Last edited: Apr 24, 2015
    duckbill likes this.
  3. duckbill

    duckbill Solo Diver

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    Here's a tip. If they charge an extra fee for it, or say it is a special test or an extra step in the test procedure, RUN, DO NOT WALK to another hydro facility.
     
  4. KWS

    KWS ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: SE TEXAS
    4,380
    1,023
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    Im no expert on it but here is what i understand. There is a ree # on the tank that tells the tester how things are to be done. when you hydro you presurize the tank to make it stretch. you measure how much it has stretched then take the presure off to see how much the tank recovered fromt he stretch. there will be rules like if it returns to less than 20% the stretch amount, it passes. if it returned to less than 10% it can have the + renewed. so presurise a tyank ans it stretches 200 mm in displacement. it if it returns to only 41 it fails if it returns to 21-40 it passes if it returnes to 20 or less it can get the + rating. Hopefully someone can explain it better. None of my tanks have the + renewed because the shop says they do not do it. Scuba tanks is a sideline as far as hydro's go for them. I do however ask them and they told me they all returned to 0% except one and that went to <2%. All + elligible but no stamp by them. If you get them hydroed and they do not + them it does not mean you loose it forever. any one can renew the + at any time. In short the lack of a + at renewal does not mean it did not qualify for it.
     
    Last edited: Apr 25, 2015
  5. duckbill

    duckbill Solo Diver

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    No. Permanent expansion must be 10% or less of the total expansion to pass hydro.

    "REE" means "Rejection Elastic Expansion".

    All the hydrotester has to do for the "+" rating is to subtract the permanent expansion from the total expansion to find the elastic expansion. Then he simply ascertains that the elastic expansion is less than the REE number, and stamps the "+" next to the hydro stamp. EASY.

    Even if the facility doesn't do it for you, as long as you have or know the REE you can get the hydro data and see for yourself if your cylinder rates the "+". If you fill your own, it's good to know for your own peace of mind.

    I've only had one cylinder fail the "+" rating that otherwise passed hydro. And that was because the idiot who previously "+" rated it thought the proper procedure was to fill the cylinder 10% over test pressure. In other words, he severely overpressurized my cylinder, removing just enough elasticity that it did not qualify for the "+" this last time around (Actually, the elastic expansion was exactly the REE). That's why I say RUN from test facilities that don't know what they are doing. There are very few true "professionals" in the world today, I am finding.
     
    halocline and tridacna like this.
  6. KWS

    KWS ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: SE TEXAS
    4,380
    1,023
    113
    duckbill,,,,,,,,,I was only using 20% for the mechanics of the explaination. I had no intent to try to quote specifics. The purpose of the statement was to say that no special testing was needed to get the + rating because all info is available upon hydro completion. Whether the tank passed in general or passed to renew the + rating was all in the test result numbers. Didnt mean to be confusing. Every thing else you said I agree with.
     
    Last edited: Apr 25, 2015
  7. redacted

    redacted Guest

    My local hydro shop (does my Als and HP100) would not do "+" qualification on some LP72s. He says it required additional training, expense, and DOT authorization. So he sent me elsewhere with those tanks.

    Make sure your facility is qualified to do the "+" testing.
     
  8. duckbill

    duckbill Solo Diver

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    Hahahaha! That's a good one! I thought I'd heard 'em all!
    Yes, with a comment like that, they certainly are not "qualified" to do a plus rating on any cylinder:shakehead: All they need is the REE. That is what most lack regarding the old 72s. Without it, no "+".
     
  9. halocline

    halocline Solo Diver

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    I went through 4 or 5 hydro test shops before finding one that would give my LP72s the plus rating, with me giving them the PST document listing the REE. My experience here in San Antonio is that most of them are idiots when it comes to scuba tanks.
     
  10. KWS

    KWS ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: SE TEXAS
    4,380
    1,023
    113
    I think you are right. Most places i have found do not do pluss or star hydros. thier primary business is not scuba related but industrial.

     

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