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  1. #1
    Join Date
    Sep 2006
    Location
    Ohio
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    494

    Propylene glycol

    I have been seeing chilled water loops that have a 30% propylene glycol, 70% distilled water solution that starts out a light purple color but turns brown after a year or less. Some have copper piping and some have black iron or steal piping. I'm thinking the glycol is picking up impurities from the piping. Has anyone see glycol water loops turn brown before?

  2. #2
    Join Date
    Nov 2004
    Location
    up in the hizzy
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    1,407
    I had seeing it, glycol itself is very abrasive to metal, now combined with distilled water, the solution will scrub the piping picking up rust and minerals, thats why the mud color. its normal, I wouldn't worry about it, always a good idea to collect a sample and have it lab tested once a year.

  3. #3
    Join Date
    Nov 2002
    Location
    NJ - WORK IN NYC AREA
    Posts
    1,476
    Valdelocc makes a good point. Most companies fill the system and forget about them. Glycol levels have to be checked, they also can become corrosive! This happens if the alkalinity changes. Seed a sample once a year out to lab.
    "My hands are for sale"

  4. #4
    Join Date
    Sep 2006
    Location
    Ohio
    Posts
    494
    I have seen very large glycol systems go for years and stay clean. The small system I'm working on now that looks dirty use to have city water and they may have added distilled water at times. It's an open loop so they have to add water to it from time to time. About a year ago the customer asked me to drain, flush and fill it with glycol. I think it's dirty from all the crap that was left in the system. I'm going to drain it and fill it with new glycol.

  5. #5
    Join Date
    Jul 2011
    Location
    East coast USA
    Posts
    997
    Quote Originally Posted by hands View Post
    I have seen very large glycol systems go for years and stay clean. The small system I'm working on now that looks dirty use to have city water and they may have added distilled water at times. It's an open loop so they have to add water to it from time to time. About a year ago the customer asked me to drain, flush and fill it with glycol. I think it's dirty from all the crap that was left in the system. I'm going to drain it and fill it with new glycol.
    Glycol in open loop?

    Yes test the water, you could have bacteria in the system as well and the brown could be the by product. I would install a bag strainer to the loop to get samples and help clean the water. Depending on how bad the particle count is it could effect your system in several ways. Talk to your chemical vendor

  6. #6
    Join Date
    Mar 2007
    Posts
    46
    Any glycol, ethylene or polypropylene, will break down to glycolic acids. Bacteria is another big problem in new or old systems. A water treatment specialist should be used to keep things tip top.

  7. #7
    Join Date
    Nov 2006
    Location
    Desert Southwest
    Posts
    709
    Just curious about using glycol in an open loop, Can you give me some more info on the type of system?
    If you can't fix it with JB Weld, Duct Tape, and Ty Wire it has to be replaced.
    No good deed goes unpunished.
    If you want to take off friday to go fishing then make sure you train your helper right.

  8. #8
    Join Date
    Sep 2006
    Location
    Ohio
    Posts
    494
    Quote Originally Posted by desert guy View Post
    Just curious about using glycol in an open loop, Can you give me some more info on the type of system?
    The system is a Process Chiller that that has a water bath evaporator and the cover of the tank is not sealed. There is also a over flow on the tank. The glycol solution circulates from the tank to a cooling jacket on a large Weld machine. I think it also cools some oil pumps on the Weld machine. The evaporator coil and most of the piping is copper. The water temperature set point is around 75 degrees f. The water will evaporate from the solution and distilled water needs to be added to keep the level up.

  9. #9
    Join Date
    Jul 2011
    Location
    East coast USA
    Posts
    997
    Quote Originally Posted by hands View Post
    The system is a Process Chiller that that has a water bath evaporator and the cover of the tank is not sealed. There is also a over flow on the tank. The glycol solution circulates from the tank to a cooling jacket on a large Weld machine. I think it also cools some oil pumps on the Weld machine. The evaporator coil and most of the piping is copper. The water temperature set point is around 75 degrees f. The water will evaporate from the solution and distilled water needs to be added to keep the level up.

    What a nightmare keeping the system clean...good luck

  10. #10
    Join Date
    Mar 2013
    Location
    Central IL
    Posts
    103
    Yes, with last years drought conditions I could only imagine how much dirt and debri entered this system. As well as bacteria and micro organisms. Sounds like you should look into adding an air/dirt seperator and filtering proccess to your system. I would also send samples to a lab for testing they can suggest an algiside and or anything else you may want inject to treat system against possible corosion of equipment.

  11. #11
    Join Date
    Jul 2010
    Location
    Az
    Posts
    74
    Quote Originally Posted by hands View Post
    The system is a Process Chiller that that has a water bath evaporator and the cover of the tank is not sealed. There is also a over flow on the tank. The glycol solution circulates from the tank to a cooling jacket on a large Weld machine. I think it also cools some oil pumps on the Weld machine. The evaporator coil and most of the piping is copper. The water temperature set point is around 75 degrees f. The water will evaporate from the solution and distilled water needs to be added to keep the level up.
    This sounds like a Berg chiller, they just have a cover over the chilled water tank that you can lift off and check the glycol level.

  12. #12
    Join Date
    Jun 2002
    Location
    Dacula, GA
    Posts
    12,859
    Why not use ethylene glycol? In most heat transfer applications ethylene glycol-based fluids are your best choice because of their superior heat transfer efficiency. This efficiency is largely due to the lower viscosity of ethylene glycol solutions. Another benefit of this viscosity advantage is lower power consumption for re-circulation pumps and a lower minimum operating temperature. You can't use it in food processing plants because of its higher toxicity.
    "I could have ended the war in a month. I could have made North Vietnam look like a mud puddle."
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    Barry Goldwater

  13. #13
    Join Date
    Sep 2006
    Location
    Ohio
    Posts
    494
    Quote Originally Posted by Abrnth3 View Post
    Yes, with last years drought conditions I could only imagine how much dirt and debri entered this system. As well as bacteria and micro organisms. Sounds like you should look into adding an air/dirt seperator and filtering proccess to your system. I would also send samples to a lab for testing they can suggest an algiside and or anything else you may want inject to treat system against possible corosion of equipment.
    This is an inside system, no dirt and the room is clean for a factory. There is also a cartridge filter in the loop. It looks clean other than the dark glycol solution. I have a new drum of glycol (30%) on site. I'm just waiting for them to give me a shutdown.

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