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Low-cost nitrox compatible home compressor?

Discussion in 'Compressors, Boosters and Blending Systems' started by Javik, Jun 30, 2020.

  1. Javik

    Javik Angel Fish

    # of Dives: 50 - 99
    Location: United States
    67
    7
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    Does anyone sell a low-cost compressor under US$3000 that is designed to be compatible with nitrox air tanks?

    Yes I have taken the PADI nitrox course. I am aware of the hazards of using a generic compressor and filling system with nitrox rated tanks.

    I do NOT want to blend oxygen and air at home. I only want to be able to refill nitrox-grade tanks with standard air, when I am unable to easily access blending facilities somewhere else.

    As far as I can tell the only difference between a generic compressor, and one that is rated for nitrox, is about $100 worth of O-rings and lubricants that are not a fire/explosion hazard in the presence of pure oxygen.

    There is no need to have to spend US$5000+ to get a compressor with nitrox compatibility.
     
  2. abnfrog

    abnfrog Tech Instructor

    # of Dives: 2,500 - 4,999
    Location: great white north
    1,755
    1,364
    113
    actually you don't understand or you would not ask that question your course SHOULD have given you that information o2 cleaned tanks CAN be filled with air if the standard air is hyper clean ..meaning going threw a hyper filter system then going in the tank ...............thats the easy answer
     
    LiteWeight, Jack Hammer and Dark Wolf like this.
  3. Javik

    Javik Angel Fish

    # of Dives: 50 - 99
    Location: United States
    67
    7
    8
    I am referring to the nitrox course for basic diving certification to use nitrox, not an advanced blending related course.

    I was under the impression that the compressor itself needs special oils and gaskets even though it is not itself ever going to be directly exposed to pure oxygen.

    So it doesn't really matter, any compressor will work, and the post filtering and oil stripping will remove any hydrocarbons?
     
  4. Jack Hammer

    Jack Hammer Solo Diver

    1,894
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    I believe he was referring to the Nitrox class. It should have covered using OCA (oxygen clean air) in a Nitrox tank that has been O2 cleaned.

    Not all compressors are ideal for O2 usage. There are ways around it but were getting slightly more advanced.
     
    Dark Wolf likes this.
  5. abnfrog

    abnfrog Tech Instructor

    # of Dives: 2,500 - 4,999
    Location: great white north
    1,755
    1,364
    113
    yes i was
     
  6. Chris H

    Chris H Barracuda

    # of Dives: 500 - 999
    Location: LaCrosse, WI
    386
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    I just had a sample from a Bauer Jr II meet the OCA specifications. It has Lawrence Factor X22679 and an X53240 cartridges, and I'm running synthetic, Oxygen safe lubricant. There is no Hyper filter on the system. YMMV
     
    nadwidny likes this.
  7. Javik

    Javik Angel Fish

    # of Dives: 50 - 99
    Location: United States
    67
    7
    8
    Thanks for an actual useful reply Chris H.

    So apparently this ideally needs:
    • a compressor that is preferably oil-free, but fully oil splash lubricated may be okay
    • post-compression air chiller
    • oil / water separator
    • grade E primary filter stack
    • modified grade E / hyperfilter secondary filter stack
    Compressor technology:
    • Oil-free compressors flex a small metal disk a few millimeters. They have a tiny air volume and will take forever without multiple disks pumping in series and parallel. Eventually the metal disk fails from flexing stress.
    • Fully lubricated compressors with pistons and piston rings will last the longest, but there is no attempt to keep oil away from the air. Due to the pumping action, all internal components are dripping with oil, and the compressed air is saturated with oil aerosol droplets when coming out of the compressor.
    Post-compression air chiller:
    • All compressors also produce water aerosols if there is any humidity in the intake air, because compressing the air makes the vapor turn back to liquid, though this does not happen immediately because compressed air is also very hot so the humidity may still remain a vapor until the compressed air cools.
    • Some oil in the exhaust air may also stay as a vapor until the compressed air cools.
    And so, there should probably be an air chiller after the compressor. Directly filling tanks with hot air from a compressor is probably a not good idea even without a filter stack and using standard non-nitrox tanks, because some water and oil vapor still remains in the hot air.

    This small amount of water will eventually condense into a few droplets when the air cools, and it may cause corrosion on the inside of the tank, or 1st stage / regulator freeze-up if diving in the winter and the tank is tilted underwater.

    Filter stack:

    The first stage filter stack may already contain an oil and water separator, but if it is just a cartridge then a separate oil/water demister / pre-separator may be a good idea ahead of it.
     
  8. nadwidny

    nadwidny Instructor, Scuba

    # of Dives: I just don't log dives
    Location: Cranbrook, BC
    1,847
    467
    83
    Actually there is an easier answer....hyperfiltration to achieve "oxygen clean air" is just hyper hype. Most compressors can meet that pseudo-standard with just the normal filters they come with.
     
    Chris H likes this.
  9. nadwidny

    nadwidny Instructor, Scuba

    # of Dives: I just don't log dives
    Location: Cranbrook, BC
    1,847
    467
    83

    I had 2 compressors (Bauer blocks) but I'm down to one now, with just normal filtration. No fancy chillers, hyper filters or any of that. I hit OCA all the time, and I tested them a lot (monthly at times). OCA every single time, even with 120hours on one of the filters this one time.
     
    Chris H likes this.
  10. lowwall

    lowwall Manta Ray

    # of Dives: 200 - 499
    Location: Chicago
    735
    605
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    Yes, but not all of us get to start with that sweet Canadian mountain air :)
     

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