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Air compressor?

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  • Air compressor?

    I've been reading about how an air compressor with the appropriate filters is a practical and effective way to aerate wort without the risk of over oxygenating. If I were to go this route what size air compressor should I use and what''s the procedure? I would think the volume of wort to be aerated, 3bbls in my case, would determine the size of the compressor . FYI, the only other use for this compressor will be washing kegs.

    Last edited by baer19d; 12-28-2017, 07:17 AM.

  • #2
    I've not heard of anyone doing this, and for good reason. If I were to consider this in the slightest bit, the cost of the compressor, dryer, filtration and analytical system, it would cost more than a standard O2 setup and a DO meter. With any cheaper compressed air setup, I'd worry SO much more about the consistency of air quality than ever over or under oxygenation. You gotta know exactly what you are pumping into your wort. It like with breweries that use just any old rotary compressor and run their keg washer directly from it. Whatever comes out of that compressor goes into your kegs.

    Now a dedicated medical-grade air compressor for wort aeration would make more sense. You can them for less than a grand now. That could be worth consideration. Other than that, I'd recommend an O2 bottle and doing the math.


    • #3
      We do both O2 and Air depending on the beer. O2 is just so much easier and not a big deal when dialed in correctly. Air can be more of a pain to dial in but if you get it right it's one less tank to fill.

      1: Best Compressor you can afford. Cheap compressors will crap out on you with heavy use. We use our compressor for inline aeration and keg washing prior to sanitization and CO2 step and that requires a higher quality compressor due to the duty cycle.

      2: Multi-stage filter to remove particulates, water, oil, etc. This is what we use:

      3: Sterilized Filter. Without this you risk contamination. Keep it clean. This is what we use and is autoclavable:

      4: In-line aeration assembly. You want this as far back from your ferm as you can get or you won't get ideal saturation and end up blowing off a ton of foam. I'm sure you can put one together cheaply but we use this:


      • #4
        Many breweries--indeed maybe most--use compressed air instead of bottled oxygen. You do NOT need any special equipment and you will not over oxygenate your beer. Almost all of them use rotary compressors with filtration. Some of the breweries I work at use NO air or oxygen at all. Just a fresh pitch of dry yeast. There is no requirement for oxygen with fresh, dry yeast. Oxygen is a waste of resource for most beers, IMO. Besides, your air demand will be far higher for a keg washer than for oxygenation, if you choose to do so. Pick a compressor based on the demand of your keg washer and it will be more than adequate for an aeration stone. And NO, you do not need an oil-less compressor, medical grade or any other such special equipment to get the same, perfectly good air that you breathe, into the wort for your yeast. Great resource for those who want to know is the book "Compressed Air In Breweries" from MBA. Great read.
        Phillip Kelm--Palau Brewing Company Manager--


        • #5
          I would agree that it is likely most breweries use compressed air over oxygen. Both make perfectly acceptable beer when used properly.

          It is advisable to use an oil-less air compressor because there absolutely will be some oil that makes its way into the compressed air. The amount may be quite minimal, and may be easily removed by a proper filter/drier system attached so you can use an oiled compressor knowing this.

          In fact, regular atmospheric air itself is very likely to have at least some oil vapor (among other things) present prior to being compressed. This comes from hydrocarbon emissions and the like. 2-5 ppm in compressed air is quite common. The air we breath is not clean. (And not just because I’m in India, lol)

          So “special” equipment would be a filter/drier (preferably a sterile filter) component after the compressor. Not too expensive or anything, but necessary for quality air.

          If you like air, another good option is a small aquarium style diaphragm pump with sterile filter disc inline. Cheap, easy, quiet, and small. Perfect for your size.

          I opt for o2 personally but have used compressed air also. I like the option of dosing high gravity wort with more o2 with just the turn of the rotometer or increased flow time. It is clean and free of impurities and I don’t have to monitor filtration status. Oxygen is also toxic to living organisms in high concentrations, so no concerns of biological contaminants.

          I will be looking into the book Philip recommended, but another good resource for technical information is the Compressed Air and Gas Institute. Very detailed (and free) information. Under education there is a compressed air and gas handbook that is very useful.


          • #6

            Clean compressed air needs a filter

            Dual filter/separator/regulator block


            I plan on running this off of an inexpensive airbrush compressor.


            Has been working great. 30 bbl brewhouse. Buy a spare compressor, they are throw away.
            Todd G Hicks
            BeerDenizen Brewing Services


            • #7
              Question on Hose Materials

              Great information.

              Follow up question: If I use a poly urethane hose after the filter (5 micron, then 0.3 micron), could it add off flavors to the beer? Typically, air compressor hoses are made of poly urethane or nylon. TIA


              • #8
                Originally posted by Earl Stephens View Post
                Great information.

                Follow up question: If I use a poly urethane hose after the filter (5 micron, then 0.3 micron), could it add off flavors to the beer? Typically, air compressor hoses are made of poly urethane or nylon. TIA
                Very unlikely, but if you are totally anal, then you would want to use platinum cured silicone like Tygon. You can go to a chemical compatibility chart to see if the planned substance will react with your tubing. Most places I know use a braided vinyl without issues.

                I think this is way down the list of things to worry about adding off flavors to the beer.


                • #9
                  Thank You

                  Thanks UnFermentable


                  • #10
                    Thanks for all the input. I'll most likely start with a reciprocating compressor in the 60-80 gallon size range with the appropriate filters. By the time it breaks I'll hopefully have the money to buy a better one.


                    • #11
                      Consider a refrigerated air dryer as part of your filtration. Also be sure to drain the condensation from the compressor tank on a regular basis; maybe even install an automatic drain. If the tank fills with condensation you'll be pumping that out along with your air.