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Air compressor experts? I have an idea...

Post in 'DIY and General non-hearth advice' started by Badfish740, Apr 11, 2012.

  1. Badfish740

    Badfish740 Minister of Fire

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    I just bought one of these:

    http://www.amazon.com/Master-Flow-M...AD2U/ref=sr_1_2?ie=UTF8&qid=1334153184&sr=8-2

    It's a cheapo made-in-China (I can hear BB running out to get one now ;) ) portable compressor that actually gets decent marks from the off-road community for its ability to air up oversize tires in a reasonable amount of time without blowing up. It's not hard to find folks who are getting many years of use out of these things. Not bad for $50-sometimes you can even find them on sale for $25. I paid $50 for mine, but I was thinking of trying to snag another one when they go on sale. These little guys put out 2.5 CFM and a max pressure of 150 psi. I was wondering, if I plumbed two of them together with a simple tee into a tank, the tank would see 5 CFM but the max pressure would stay the same, correct? There's actually a nice little tutorial on 4x4wire that shows how to take them apart and port them with a Dremel for more flow, maybe 3 CFM, so if my theory is correct, that little trick would result in 6-7 CFM to the tank. That would be about equivalent of a good OBA system using a repurposed vehicle AC compressor, with the advantage of less underhood plumbing and the ability to move the thing around if need be. The other big question is electrical in nature-these things draw 30A at full load. The write up that I saw used 10GA wire for one compressor, so for a similar run (let's call it 8' from the battery) for two compressors what should I be using? 6GA with a 60A inline fuse? Or just run two 10GA lines with separate 30A fuses?

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  2. heat seeker

    heat seeker Minister of Fire

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    Yes, you would double the CFM, but the pressure would peak at the unit with the highest setting.

    Porting the unit might give you more CFM, but could the motor take the extra stress?

    I'd run two separate wires and fuses, so if I wanted to move one elsewhere temporarily it would be easier.
  3. Flatbedford

    Flatbedford Minister of Fire

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    If it is a good unit, maybe I'll pick one up. I have thrown away a couple Sear units that I paid more for and had much lower performance.
  4. kettensäge

    kettensäge Feeling the Heat

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    You should not use a tee unless it is bigger than both lines feeding into it. Any way to have two separate tank inlets and not use a "T"?


    I think porting the compressor will make it easier for the motor to push air, especially if it's on the discharge side.
    MasterMech likes this.
  5. MasterMech

    MasterMech Guest

    Ketten has a point, make sure the line size has enough capacity for the flow you're after. I imagine it wouldn't have to be that big for 7 CFM.
  6. nate379

    nate379 Guest

    2.5 CFM at what pressure?

    I have a similar one of those I keep in the truck just in case. It's not very fast, but it does the job. I never timed it, but I'd guess about 8-10 mins to fill a 35" tire.
  7. Badfish740

    Badfish740 Minister of Fire

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    It doesn't say-all it gives is the 2.5 CFM and a max pressure of 150 psi. I would set the pressure switch on the tank to cut off at 110 or so anyway so as not to stress it.

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