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tank fill rate

Discussion in 'Tanks, Valves and Bands' started by HeatCker, Sep 17, 2016.

  1. HeatCker

    HeatCker Solo Diver

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    what is the correct or usual rate at which an empty tank is filled .... ie ???? psi per minute
     
  2. tbone1004

    tbone1004 ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: I'm a Fish!
    Location: Greenville, South Carolina, United States
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    luxfer says to fill between 300-600psi/min. Not sure I've seen one out for steel tanks though they get quite hot even at a 500psi/min fill rate
     
  3. Basking Ridge Diver

    Basking Ridge Diver Solo Diver

    # of Dives: 200 - 499
    Location: New Jersey
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    I have been know to fill between 100 and 200 per minute - I have lots of time on my hands and generally only fill 4 bottles at a time. I am lucky I have access to my own compressor - I try to keep the tanks as cool as I can. I fill both aluminum and LP steel tanks.
    I have occasionally gone over 500 psi but that is too hot for my liking and only when I am really in a hurry. I want my tanks to last - this is not official this is what I do based on past experience and limited knowledge on tank expansion and heat transfer.
     
  4. spectrum

    spectrum Dive Bum Wannabe ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: The Atlantic Northeast (Maine)
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    The 600 PSI/ minute number is common. I think I have seen CGA guidance more like 300-400 PSI/minute.

    SCBA rapid refills have become quite common on the order of 45 seconds for aluminum and composites. See here.

    I have a LDS that ca do a 30 second fill. :(

    Pete
     
  5. bl6394

    bl6394 Cave Instructor

    # of Dives: 1,000 - 2,499
    Location: Mansfield, TX
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    Also depends upon what you are filling the tank with... O2 (50-60 psi/min). Nitrox (200 psi / min). Air (400-600 psi/min)
     
    WarrenZ likes this.
  6. bl6394

    bl6394 Cave Instructor

    # of Dives: 1,000 - 2,499
    Location: Mansfield, TX
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    The gas temperatures you get from compression heating are considerable - approaching 700 degrees F. Not good for the cylinder. And when it cools - you'll loose 15% of the pressure (e.g. 3000 hot may cool to 2600). Not a good practice.
     
  7. DEdiveguy1

    DEdiveguy1 Angel Fish

    # of Dives: 500 - 999
    Location: North Georgia
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    In its Fill Station Operator Hazmat training, PSI recommends filling air at 300-600 psi/min, nitrox at 200 psi/min, oxygen at 60 psi/min.
     
    KWS and BurhanMuntasser like this.
  8. HeatCker

    HeatCker Solo Diver

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    thanks for the info guys
     
  9. nadwidny

    nadwidny Instructor, Scuba

    # of Dives: I just don't log dives
    Location: Cranbrook, BC
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    Do they say why they recommend those rates?
     
  10. bl6394

    bl6394 Cave Instructor

    # of Dives: 1,000 - 2,499
    Location: Mansfield, TX
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    It's not just PSI - it's also a recommendation from a number of agencies (TDI, PADI) with respect to blending technique.

    Slow fills for O2 prevent compression heating (adiabatic compression) that could result in ignition. The lower the concentration of oxygen - the lower the risk of igniting hydrocarbons or seals in the system. Hence the faster fill rates for lower fractions of O2.

    But that is a qualitative argument. And no, I have not seen a quantitative argument to why 60 for O2 is better than 40 or not as good as 100.
     

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