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Good compressor for infrequent use?

Discussion in 'Compressors, Boosters and Blending Systems' started by 84CJ7, Nov 16, 2019.

  1. SurfLung

    SurfLung Nassau Grouper

    # of Dives: 200 - 499
    Location: Central Minnesota
    112
    113
    43
    Buying a used compressor and fixing it up... It's questionable whether you save any money. I bought a RIX SA3 used for $750 but I've been working on it and spending on it every year... It's a labor of love so I haven't kept an accurate tally of how much I've spent. I bet it is as much or more than the $2700 for a new Coltri MCH6. Last Summer I bought a 1980 Aerotecnica Coltri MCH6 for $250. Very similar to the current model. I've had to repair the gas engine, fabricate a moisture dissipator and remote air intake for the compressor, but it runs like a top now. For me its been fun learning these machines as I invested time and money fixing them up. But I think anyone who wants the simplest most reliable solution should go with the New Coltri MCH6... And at $2700 is is a bargain.

    P.S. Owning a compressor is not just about saving money on air fills. The CONVENIENCE of filling your own tanks is awesome... I think convenience is the biggest advantage.:)
     
  2. spoolin01

    spoolin01 Solo Diver

    # of Dives: 500 - 999
    Location: SF Bay Area, CA
    1,527
    211
    63
    The RIX were more expensive to begin with - are rebuild/repair parts more expensive than the alternatives? I've always figured the savings with oil-less were in the cost of oil and the added needed filtration.
     
  3. ofg-1

    ofg-1 Course Director

    257
    515
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    Best compressor for infrequent use is someone else's.
     
  4. Scuba Lawyer

    Scuba Lawyer Barracuda

    # of Dives: 5,000 - ∞
    Location: Laguna Beach, California
    426
    983
    93
    I've been researching the bejesus out of compressors for occasional use (defined by me as maybe 4 fills a month). The Alkin W31 (110 or 220) meets all my needs and, from what I gather, is well engineered. The last time I looked the retail price was around $2,700. At DEMA a year ago Alkin had a show special of around $2,250 complete out the door if you put a $100 deposit down at the show.

    I don't really NEED a compressor as much as I WANT a compressor so as to divorce myself from dive shops forever (another long story for another day). :)

    Anyway, as fun as it would be to acquire and rebuild an old compressor, for the price I'm going shiny and new. My 2psi.
     
    tmassey and SurfLung like this.
  5. tbone1004

    tbone1004 ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: I'm a Fish!
    Location: Greenville, South Carolina, United States
    15,737
    7,070
    113
    yes, the parts are quite expensive because they have all of the traceability requirements for military supply. A lot of the jokes about a $10 o-ring are real when you have to inspect every single one by hand and have paperwork to follow it. Sure it only cost $0.02 to make, but the testing and paperwork are the rest of it. Every part on them is expensive and if you buy a used one, I would say to budget about $2k to rebuild it. The advantage though is they don't NEED any other filtration, especially if using aluminum tanks, and if you use steel, they really only need an extra coalescer since there is nothing else to filter out. Add in no oil-changes and you have a lower operating cost which is nice. They can also be mounting in any orientation and if you travel, don't have to worry about any potential oil leaks which is nice. They were designed to be stuck in a RHIB with the SEALS and bashed around. If that works for you, then it may be worth it. If it's sitting in your garage? Just buy the Coltri.
     
    Dark Wolf and SurfLung like this.
  6. SurfLung

    SurfLung Nassau Grouper

    # of Dives: 200 - 499
    Location: Central Minnesota
    112
    113
    43
    I am proud to own a RIX. But they can be a little tedious to maintain in top performance. For example, moisture in the air combines with teflon dust from the wearing of the teflon rings. This gradually gums up the ring expansion and diminishes the seal... So a few months after you have it running at a full 3.0 cfm, it might be running from 2-2.5 cfm. I've found that the teflon rings can be "refreshed" by taking out the pistons and washing them (with the rings) in Dawn detergent. You can see and feel the rings ability to compress and expand being restored as the gunk is cleaned off. Dry everything thoroughly before re-assembly.

    - As for O-Rings... Don't be like me. I got impatient and just wanted to get it back together and fill tanks. Hardware store O-Rings fit fine and seemed to run fine. But they really didn't. They either extrude or melt and cause leaks.The manual specs Viton 90 for the heads and I bought a lifetime supply of these (correct O-rings) for pennies from the O-Ring Store.

    But as T-bone said, RIX were built for the military. Money is no object there. Rix are easy to take apart and re-assemble. Military can just replace all of the O-rings and teflon rings and the thing runs like new again. It's quick and easy when you have new parts and you've done it a few times.
     
    tbone1004 likes this.
  7. spoolin01

    spoolin01 Solo Diver

    # of Dives: 500 - 999
    Location: SF Bay Area, CA
    1,527
    211
    63
    $2K! What are you replacing that costs so much? It's been a few years, but I rebuilt a SA-3 that I got in pieces and I'm pretty sure I didn't spend more than about $300-$400, if that. That included all the wear ring stuff, o-rings, a cylinder sleeve, and a couple odds and ends of small hard parts as well. That's why I wondered how it compared to other brands, since it didn't seem that costly.
     
  8. SurfLung

    SurfLung Nassau Grouper

    # of Dives: 200 - 499
    Location: Central Minnesota
    112
    113
    43
    - You're right about the regular maintenance costs. And if you don't need any major parts replaced, that may be all you need. But over the years I put a lot more into my used RIX SA3:
    1. Purchased a used filter array with fill whip - $600. (Rix don't come with filters, just condensers - RIX factory filter is $3200 I think)
    2. Purchased a new 3rd stage condenser to replaced cracked original. - I think is was $400 without guts.
    3. Purchased a new 3rd stage piston (list $750 complete - I got the parts unassembled for about $350.
    4. I spent a few more dollars on various expensive pulleys/sheaves to find the one to give almost exactly 2300 RPM (and 3 cfm). My used purchase did not have the original pulley nor the original motor.
    5.But considering the SA-3 was listing for $6,000 new, I'm still way under that with a bargain in spite of my repair costs.
    - The latest price list for parts is available directly from RIX and the prices seem substantially higher since they stopped manufacturing the SA3 and SA6. BUT, the parts ARE available and the factory is still there so you can call for tech support.
     
  9. tbone1004

    tbone1004 ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: I'm a Fish!
    Location: Greenville, South Carolina, United States
    15,737
    7,070
    113
    If you purchase the standard maintenance kit, as of Dec 2018 for the SA6 it is $1201. In 2006, it was $665, so parts have come up quite a bit in the last decade unfortunately. Don't know what the SA3 is, but I imagine it is about the same. In 2018, that does include $350 worth of the Krytox grease and the inlet filter which I would argue you don't need to buy, and that's up from $200 in 2006. Figure add in a grand of "just in case" and you're good, or adding a filter tower etc.
     
  10. spoolin01

    spoolin01 Solo Diver

    # of Dives: 500 - 999
    Location: SF Bay Area, CA
    1,527
    211
    63
    Went back and looked at the quote from RIX in 2012 for the SA-3. Without the grease and filter it was around $700 - must have gotten some of the rebuild parts when I bought the compressor. Sorry to hear it's gone up so much, wish I'd bought the SA-6 parts at the same time...

    Still, how does this compare to what it takes to rebuild a similar capacity Bauer/Coltri/etc?
     

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