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centrifuge pump for moving mash to lauter tun

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  • centrifuge pump for moving mash to lauter tun

    We are using a centrifuge pump for moving mash to the lauter tun. We have a vfd on the pump and are wondering what is the max rpm we should be using when pushing the mash to the lauter. We are currently running at almost full rpm 3420. If I had my choice I would change to an impeller pump, but the centrifuge pump is what we currently have in place.

    It's a new system and we are 2 for 2 with stuck mashes. I bought sleeves and tested the milled grain size. We have a grant so we are not compressing the grain bed while lautering, and I open the lauter valve very slowly.

    So my question is, are we beating up the grain with running a centrifuge pump at high rpms? If so, what is the suggest rpm we should be using to push the mash?

  • #2
    What exactly do you mean by "centrifuge pump"?

    We pump mash over with a centrifugal pump with an open impeller, the classic C-series style that Alfa Laval, Ampco, etc all make. We run at about 60% on the VFD.
    Linus Hall
    Yazoo Brewing
    Nashville, TN


    • #3
      Yes, centrifugal pump, ours is also an open impeller. Do you know the RPM of your pump at 60%?


      • #4
        What are the specifics of your pump? Model, HP, connection size, and impeller size.
        Your CPE Systems Team!
        CPE Systems Inc.


        • #5
          It's a just bit more complicated than simply say what speed do you run the pump at. First of all, the recommended rates of transfer need to be considered - 10 minutes transfer time, with a transfer flow rate of 1.5 metres / sec - JUST turbulent flow in clear liquids. So if your pipe work is too narrow, you have to transfer too fast, which means both the pump, whichever sort you use, and the high flow rate are likely to damage the mash particles. Having worked out what mains size you need to achieve turbulent flow, then you can size a pump. They should be low shear pumps, again, the EBC best practice manual says an open impeller, actually very different from the design that has been suggested - the picture attached is the sort they recommend. Then they recommend maximum 1,000 rpm - far less than you are currently using. I have seen high speed centrifugal pumps used in a couple of places - both open impeller similar to that suggested, and another using a closed impeller - all were destroying the mash leading to set mashes, slow and poor quality runoffs, with poor extracts (not helped admittedly by appalling rake design and operation).
          Attached Files


          • #6
            Calculating the velocity with pipe dimensions before the pump 51mm, and the pump exit 25mm, our Reynolds number exceeds laminar for the 25mm pump housing opening. I will definitely bring the rpm down under 1000, and calculate the velocity based on our smallest pipe opening. I attached pictures of our impeller and pump housing.


            • #7
              I'd use a flexible impeller pump. Positive displacement, gentle handling, lower rpms, and you can run them either way to pump to or from MT. There really isn't a downside to them.
              Phillip Kelm--Palau Brewing Company Manager--


              • #8
                I was talking with a rep from CPE, while they recommend helicoidal pump, our brew house is only 5bbl and they suggested that it may be a bit too much pump for us. I'm thinking their 3hp flexible impeller pump.