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Generator Exhaust

Weezbo Member Posts: 6,232
quite a few years back we picked up a piece of paper from Catapillar ...it looked basically like our circ pump charts ...

Cat would be my First thought..

Then EPA...

This guy would know....


  • JBW_2
    JBW_2 Member Posts: 67
    Generator Exhaust

    Hey Guys,

    Sizing a generator exhaust...
    We do a lot of nat. gas and propane generators, but this is our first diesel generator. So, I downloaded this Cummins exhaust software. Does anyone have experience with this? Also, are there better free softwares out there?


  • Brad White_9
    Brad White_9 Member Posts: 2,440
    Try this

    Professional Courtesy Only - No liability inferred. The generator manufacturer should review and accept all generator sizing.

    Typically the generators can tolerate 28 inches ESP (one PSI). The muffler is a big part of that, up to and over half sometimes.

    This is based in Schedule 40 steel. Metalbestos and others making UL listed generator exhaust systems may also have programs. Cummins, Kohler, Caterpillar and Onan all have OEM software but may be available only to their vendors (specific to their machines). Use your representative and wisely.

    Still, the attached spreadsheet I developed (based on Caterpillar's handbook) is a fun tool.
  • GMcD
    GMcD Member Posts: 477

    I will re-iterate Brad's comment that the gen-set manufacturer must be involved to size the exhaust pipe, especially critical with diesel turbo-charged engines with very low residual backpressure after the turbo and the muffler.

    Don't forget the high-temperature insulation on the pipe, and the wall or roof thimble requirements for the different operating exhaust temperatures of diesel vs other fuels with normally aspirated and turbo-charged carburettor systems.
  • Brad White_9
    Brad White_9 Member Posts: 2,440

    Thanks, Geoff;

    I forgot to add in my haste some of your excellent points on insulation. More specifically, if you do use a lighter weight UL listed system, they have backpressure relief fittings (burps!) to absorb backfire pressures. Without them you could rupture an elbow. Schedule 40 is the way to go, IMHO. And the temperatures? Check your expansion tables.

    You put 1200 degree F. hot gasses into a cold steel pipe and Pfizer will make an advertisement using your system as an example. ;)
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