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  1. #1
    Join Date
    Jun 2006
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    Glycol loop bacteria

    I have a chilled water/ glycol loop that cools a couple of high dollar cancer treatment machines. These loops had some biological growth (Black Slime) that was plugging my in line filters. I killed the stuff with a commercial biocide, but did not use a dispersant so some of the stuff is still on the tank walls and who knows where else. My water still tests no bacteria. The problem now is that the filters are plugging up although they look clean. I'm not sure if it is a viscosity issue or if our filters are too fine at 30 micron. I cannot tell what the % glycol is. I do not know what size filters were originally in the system. I also don't know if this new batch of filters is finer than the previous ones. I haven't personally purchased them and assumed they were the same. Any help will be appreciated. Thanks, Ken

  2. #2
    Join Date
    Aug 2000
    Austell, Ga.
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    Not sure what type "Glycol" you are using, but regardless be it Ethylene or Propylene, it "Must" be of the inhibited variety. Most glycols furnished are of the "Uninhibited"(Low dollar) and will absolutely degradate to a yuckie mess that is difficut to clean up & out of system.
    To quote Dow about the use of Glycols;

    An industrially inhibited glycol is essential in HVAC systems with steel piping to prevent fouling, clogging, and the buildup of precipitated solids. The special inhibitors developed for DOWTHERM inhibited ethylene glycol and for DOWFROST inhibited propylene glycol fluids not only buffer the acids as they are formed, but also passivate metal surfaces to control corrosion further.

    Or..... you can disregard Dows advise & stick any low dollar Glycol into a system and pay the clean up costs at some later date...
    Ain't "None" of us as smart as "All" of us..

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