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Max Helium fraction continuous blend

Discussion in 'Compressors, Boosters and Blending Systems' started by Tyler duran, Nov 8, 2019.

  1. michael-fisch

    michael-fisch Manta Ray

    # of Dives: 2,500 - 4,999
    Location: Germany
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    That sound like the explanation for DIR Standard Gasses, which are all mixes that can be made by adding 32% to Helium.

    Michael
     
  2. rjack321

    rjack321 Captain

    # of Dives: 1,000 - 2,499
    Location: Port Orchard, WA
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    I just pump 100% helium then pull out my wine cork/garbage bag from the stick inlet and switch to 32% to top off. It pushes all the helium through and into my tanks. Dont need to CB trimix at high pressures that way
     
  3. Tyler duran

    Tyler duran Angel Fish

    # of Dives: I just don't log dives
    Location: San Diego, CA
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    Rjack has the ticket. I wanted to pump raw helium 1st because it simplifies mixing a lot. With the extreme cost and availability issues with He doing it this way you can easily identify exactly where the gas is being used or wasted.

    while I haven’t tried CB’ing tri-mix with all the gases flowing through the stick at the same time, I highly suspect that it can’t possibly be as accurate as isolating one of the gasses individually first.

    Additionally since I’m only dealing with pure He on the first phase of fill my need for a He analyzer is debatably minimal. If I nail my target temps and pressure on the He fill it’s just basic math and an O2 analyzer for the last phase of fill. For the time being I’m using an He analyzer in addition to an O2 sniffer to ensure my process is viable.

    I’ll post up compressor specs later but the monitoring was exactly what you’d expect. Laser thermometer on the key component surfaces and visually examining the oil sight gauge “bulls eye.”

    I’ve got several samples drawn however I’ll have to wait until Tuesday to send them out. I’m sending out a samp of: raw unpumped fresh out of the K He, raw He pumped out of the compressor, a final sample of the finished 21/35, and an air samp off the compressor.

    I’m tempted to send off a lean nitrox sample too but that’s probably overkill. I might do that if this report indicates my O2 CB’ing muttled my 21/35’s numbers.

    I was tempted to “stir” the tanks but they were all doubles and my back can only handle so much fun. It was easier to just park em over night.

    I only started this experiment because the timing was right. I got the He on trade, I was planning on overhauling the compressors top end this winter anyways, and I got a few deeper dives I’ve been wanting to do but didn’t want to foot the gas bill.
     
  4. rjack321

    rjack321 Captain

    # of Dives: 1,000 - 2,499
    Location: Port Orchard, WA
    9,059
    2,919
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    Why are you sending helium off for analysis?

    If you recycle leftovers you really need a helium analyzer.
     
  5. Tyler duran

    Tyler duran Angel Fish

    # of Dives: I just don't log dives
    Location: San Diego, CA
    7
    2
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    I couldn’t get a lab report on it from the manufacturer and I wanted to see how clean the He was before it went through the compressor.
     
  6. KWS

    KWS ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: SE TEXAS
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    I just had my capitano revalved and ringed snf 3rd stage replaced. I used lawrence factor supplied parts. I found out too late that those parts were not Bauer parts but similar parts. when the rebuild was done the shop said I had a high blow by. 1.5 cu ft per minute @ 3000 psi as opposed to about point 7 which was normal. when it went in for rebuild it probably had a 5 cu ft per min blow by. that would make pumping He real expensive.
     
  7. michael-fisch

    michael-fisch Manta Ray

    # of Dives: 2,500 - 4,999
    Location: Germany
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    Blowby leaks into the crankcase, and the crankcase is ventilated into the 1st stage intake.

    Blowby reduces efficiency, but no gas is lost since it gets sucked back into the 1st stage on oil lubed compressors.

    Michael
     
    rjack321 and taimen like this.
  8. rjack321

    rjack321 Captain

    # of Dives: 1,000 - 2,499
    Location: Port Orchard, WA
    9,059
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    even 99.99% helium is cleaner than ambient air in san diego lol
     
    Tyler duran likes this.
  9. Tyler duran

    Tyler duran Angel Fish

    # of Dives: I just don't log dives
    Location: San Diego, CA
    7
    2
    3
    The blow by contributing to waste is bunk. As it’s been stated it’ll just recirc back to the 1st stage. Additionally you’re not going to pump He at high pressures most of the time. At lower pressures blow by is far less.

    SD air quality is bad, hopefully bad enough to hide any contaminates my compressor address :wink:
     

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