• Welcome to ScubaBoard


  1. Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

    Benefits of registering include

    • Ability to post and comment on topics and discussions.
    • A Free photo gallery to share your dive photos with the world.
    • You can make this box go away

    Joining is quick and easy. Login or Register now by clicking on the button

Neutral Buoyancy AL Tanks

Discussion in 'Tanks, Valves and Bands' started by GP, Oct 9, 2001.

  1. GP

    GP Manta Ray

    # of Dives: 200 - 499
    Location: MN
    633
    0
    0
    I noticed on http://www.divesales.com they have a 3300 psi aluminum 80 cu. ft. tank that is supposed to be neutrally buoyant when empty and -5.8 when full. Are these decent tanks? They are listing them at $140.00 plus $20.00 shipping and I am wondering if anyone has used these. Seems like a good price. Also, because it is 3300 psi does that mean that it is a HP tank and not an LP tank?

     
  2. syruss32

    syruss32 Manta Ray

    673
    1
    0
    I haven't used one but my LDS has one in a designer brushed aluminum. I wish I had known it was a neutrally boyant tank because I already have to wear too much lead and when the tank gets empty it is worse.

    If you get it let me know what you think of it?
     
  3. GP

    GP Manta Ray

    # of Dives: 200 - 499
    Location: MN
    633
    0
    0
    I guess my main question is whether or not it is a high pressure or low pressure tank. I am concerned because I have heard that HP tanks are hard on your regulators and I haven't heard of a 3300 psi LP tank before.
     
  4. WantToBe

    WantToBe Angel Fish

    61
    0
    0
    I think it is a LP tank but someone could confirm that.

     
  5. Diverl

    Diverl Angel Fish

    62
    1
    0
    All of the Neutral AL80's I have seen have been K Valves. Almost all of the AL100's I have seen have been 3300 PSI as well and they are all K Valves.

    You can purchase 3300 PSI k valves. A standard K valve is usually 210 BAR and you can get 230 BAR K valves.

    14.7 PSI/ATM * 210 BAR = 3087 PSI
    14.7 PSI/ATM * 230 BAR = 3381 PSI

    An insert can be purchased for most 230 bar DIN valves allowing them to be converted to Yoke. 300 Bar din does not have this option.

    On the http://www.divesales.com web you can choose what pressure rating you want your K Valve to be 2400 PSI, 3000 PSI and 3300 PSI.

    Just to make sure, I would email divesales or ask your lds about the specific tank that you wish to purchase from them.
    Even though the tanks take a K valve I would not really consider them to be low pressure, but that is simply my personnel opinion.

    Hope this helps!

     
  6. roakey

    roakey Old, not bold diver ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: Colorado Springs, CO
    3,580
    179
    63
    Most people think 1 BAR = 1 ATM, it's close but not exactly the same. It's close enough for handwaving, but if you're going to go to the ten's place on a conversion, you should use the correct value for BAR.

    1 BAR = 14.5 PSI, not 14.7.

    Roak
     
  7. Diverl

    Diverl Angel Fish

    62
    1
    0
    Thanks for the correction on the conversion from ATM to BAR. I was unaware that it was 14.5 PSI per bar. The stupid conversion chart I have indicated 14.7.

    Thanks!
     
  8. roakey

    roakey Old, not bold diver ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: Colorado Springs, CO
    3,580
    179
    63
    Is that every unit is based on every other unit, no matter how little sense it makes. :)

    Metric pressure is measured in something like micro dynes per fortnight meter lumens or somesuch, (ok, it's really in Pascals or Kilopascals) and no one had a good feel for how much pressure, say 1 million pascals was.

    But, lo and behold, 100 KiloPascals (kPa) was just about the same as atmospheric pressure, and atmospheric pressure everyone had a good feel for, so they created a new unit, BAR. Not quite 1ATM, but close.

    Actually most marketing information appears to use the conversion that 1 BAR = 15psi (which is why valves on a 3000 psi cylinder are thought of as a 200 BAR valves) to make the answers even more wrong!

    Roak

    Ps. What about 1 million pascals? Well that's 10 BAR, and you probably have a good feel for 10 BAR, like "about" 330 feet deep (not including atmospheric pressure)!
     
  9. Divemstr13

    Divemstr13 Angel Fish

    38
    1
    0
    Luxfer's NB 80 is: 3300 psi / 228 bar
    77.4 cu ft / 2190.9 ltrs
    outside dia 7.25
    SW buoyancy; -7.3 full/-4.4 half/-1.5 empty
     

Share This Page