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Air Compressor - rotary screw, VSD?

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  • Air Compressor - rotary screw, VSD?


    I am in the process of sourcing an air compressor for our new plant. I have a premier 3 head washer and a WGC-250 canning line on the way. Each requires 14-16 CFM and our brew system also needs 100 psi for the pneumatics but negligible CFMS.

    I am looking to over spec it a little because we hope to add a small rotary bottling line in the next 1-2 years and use a mobile bottler in between. I am looking for a 15 HP Rotary screw, oil fed machine with a variable speed drive.

    I have narrowed it down to a Curtis, an Ingersoll-rand, and an Atlas Copco. I have heard that even though you can buy integrated air dryer units, it results in higher maintenance costs than using an external drier. I have also been told not to buy an oilless model, as they require more maintenance and the oil separator works just fine on the oil fed models.

    Anyone have good or bad experiences with these machines? One technician I spoke to recommended marrying a 5 and 10 together, noting I could still operate either the canning line OR the washer on one of the compressors should the other break.

    Eric O'Connor

    Thorn Street Brewery
    North Park, San Diego, CA

  • #2
    For the Longer Term

    Eric, please look for former threads on this subject as there is a good bit of information.
    Definitely I would advise a separate Drier, and for the money you are advised to add a large external receiver.
    This will widen the interval between cycles which is helpful when the load increases down the road.
    2 units are way better than one as you have redundancy, but I would have them the same size.
    There are invariably a lot of mistakes made with this type of system that can be avoided by common sense.
    While air compressors can be located outside, they are more complicated when one does so, as you often time have to implement freeze protection measures in unexpected locations to make them operate. They are far best off in a ventilated mechanical room.
    Your Drier must be indoors in conditioned space. You are removing water, a key point to remember.
    For quiet, rugged, and reliable...the Rotary VANE units are the choice although first cost is higher.
    Your piping needs to be sized correctly and you need filtration pre and post drier of the correct type.
    Your receiver goes after the drier in the system. Its good to look at Engineered layout diagrams for this type of system for component arrangement and piping.You need auto drains in the correct locations, isolation valves everywhere, and gauges in prominent places.
    Warren Turner
    Industrial Engineering Technician
    HVACR-Electrical Systems Specialist
    Moab Brewery
    The Thought Police are Attempting to Suppress Free Speech and Sugar coat everything. This is both Cowardice and Treason given to their own kind.


    • #3
      Indeed, this has been discussed many times here.

      We use a 5 hp I-R rotary, backed up by a 5 hp Devibliss recip. The two 80 gal. reservoirs are plumbed in parallel, so we have 160 gal of storage. We then use 30 gal compressor tanks at each high-draw point-of-use station (bottler, keg washer/filler), plumbed to the air main @ 125 psi w/high-flow secondary regulators to the machines. This allows the machines to draw very large amounts of air periodically.

      I'd recommend 3/4" mainlines, regulated to 100-150 psi, for your mains, w/regulators at the POUs, and surge tanks as above at high-use machines. Same for CO2.

      PEX is excellent for mains and drops. It's quick and easy to install, and inexpensive. Just don't push the pressure limits on it.

      Whatever you plumb your air and gas with, DO NOT USE PVC! PVC embrittles with age, and shatters into horrible shrapnel when it fails under pressure.
      Timm Turrentine

      Terminal Gravity Brewing,
      Enterprise. Oregon.


      • #4
        Good reading.....

        Compressed Air In Breweries.
        Good stuff. Everyone with compressed air in their brewery should educate themselves with this book.
        Phillip Kelm--Palau Brewing Company Manager--