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"pro" (combination) tank valves

Discussion in 'Tanks, Valves & Bands' started by sandanbob, Jun 15, 2021.

  1. tbone1004

    tbone1004 Technical Instructor ScubaBoard Supporter

    # of Dives: I'm a Fish!
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    that I will not disagree with you on
     
  2. sandanbob

    sandanbob Contributor

    # of Dives: 100 - 199
    Location: United States
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    How often do you need to replace crush washers? The DGX Pro valve is $39, plus the $4 insert, total of $43. The Thermo valves ("B"- taken off tanks) were $25, including the insert. So, $18 difference.

    A service kit, that will work for both, is $16, while the crush washer (if I am reading it correctly) is $2.

    Since I ordered the Thermos, and they have shipped already, I'll try those out. My tanks need to be hydro'd anyway, so the valves will need to be removed, and replacing with the new ones will be simple.

    Thanks for the input!
     
  3. happy-diver

    happy-diver Skindiver Just feelin it

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  4. rjack321

    rjack321 ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Port Orchard, Washington State
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    In air service, overhaul the whole valve at hydro time. So once every 5 years.
    Trying to keep it O2 clean? Every 6 months to 2 years depending on use.

    If the stem oring gets crusty or starts to leak (probably one of the most common leaks) you have to remove the bonnet nut to access that oring and that means replacing the crush washer. Of course that all assumes you get it out without damaging the valve body. They sometimes corrode in place (if left too long - 5 years is sometimes too long) and are impossible to pick out.

    Crush washers suck, its a poor design.
     
    rob.mwpropane and rhwestfall like this.
  5. sandanbob

    sandanbob Contributor

    # of Dives: 100 - 199
    Location: United States
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    Interesting. So, why would they continue to make and sell ones with a crush washer, if they can be so problematic?

    I am learning more about valves. Thanks!

    If these don't work well, I can trade back the old valves, or look into other options like the DGX.
     
  6. 2airishuman

    2airishuman Contributor

    # of Dives: 100 - 199
    Location: Greater Minnesota
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    The goal of the Thermo design is to avoid having the gas in contact with the bonnet threads. It is a common approach in industrial cylinder valves where the gas may be more corrosive than the atmosphere, or where the threads may be a source of unwanted impurities.

    I'm not sure the design serves any useful purpose for scuba valves, but I find it to be, at most, a minor nuisance.
     
    rob.mwpropane and rjack321 like this.
  7. tbone1004

    tbone1004 Technical Instructor ScubaBoard Supporter

    # of Dives: I'm a Fish!
    Location: Greenville, South Carolina, United States
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    only when you take the bonnet off, which should be no more than 5 years when you service, but happens if you shear the valve knob off. It's a minor nuisance and is a bit annoying compared to a cheap o-ring and also requires some more torque when you put it back, but it's not going to cause you to go to the poor house on a pair of tanks.
     
  8. rjack321

    rjack321 ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Port Orchard, Washington State
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    Yeah but when you have 40+ tanks and valves it adds up! I get the -015 size in lots of 100 on Mcmaster for ~$8ish
     
    Johnoly likes this.
  9. tbone1004

    tbone1004 Technical Instructor ScubaBoard Supporter

    # of Dives: I'm a Fish!
    Location: Greenville, South Carolina, United States
    18,800
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    I don't know if I have 40+, but it's close to it, thankfully most of them are OMS and/or Dive Rite valves which use o-rings.
     
    Johnoly likes this.
  10. Johnoly

    Johnoly Contributor

    # of Dives: 2,500 - 4,999
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    Based on the FtL purchase link you sent,,,,every 3-4 years I'm tossing whole valves in the trash can and screwing in new thermo's. Even cleaning and doing everything myself > which is easy,,,,,,,I still can't beat that link. Half doz in the new parts bin just waiting. Thank you again !!
     

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