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  • Propylene Glycol

    I received the Chill & Flow chiller that I ordered from ProRefrigeration and am almost ready to fill it up and start pumping it through our system.

    I purchased USP food grade, 99.9% pure propylene glycol. I was planning on using my RO/DI water filter to mix with the glycol. Do I need to add any corrosion/rust inhibitors to my solution?

  • #2
    Inhibitor

    Originally posted by d_striker View Post
    I received the Chill & Flow chiller that I ordered from ProRefrigeration and am almost ready to fill it up and start pumping it through our system.

    I purchased USP food grade, 99.9% pure propylene glycol. I was planning on using my RO/DI water filter to mix with the glycol. Do I need to add any corrosion/rust inhibitors to my solution?
    There are inhibitors available, but I am wondering why you did not just by the correct glycol product with the inhibitor already in it from Pro? They have exactly what is needed.
    I would not suggest using RO or DI to dilute as they are both much more corrosive than tap water, especially DI.



    SC
    Warren Turner
    Industrial Engineering Technician
    HVACR-Electrical Systems Specialist
    Moab Brewery
    The Thought Police are Attempting to Suppress Free Speech and Sugar coat everything. This is both Cowardice and Treason given to their own kind.

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    • #3
      How is DI water more corrosive than tap?

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      • #4
        Taking all the minerals out of the water makes it hungry for all other availible items, particuarly metals. Best explanation from a mate who is in water treatment.

        I can get 'raw' glycol half the price of one premixed, so having the same issues when i need over 3000l in total of glycol. Trying to find the inhibitors now ...
        Head Brewer Rocks Brewing Co.
        Sydney, Aust
        scotty@rocksbrewing.com

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        • #5
          Originally posted by scmorgan View Post
          Taking all the minerals out of the water makes it hungry for all other availible items, particuarly metals. Best explanation from a mate who is in water treatment.

          I can get 'raw' glycol half the price of one premixed, so having the same issues when i need over 3000l in total of glycol. Trying to find the inhibitors now ...
          Good explanation. I assumed distilled water was less corrosive as that is what you're supposed to use in car radiators to minimize corrosion.

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          • #6
            glycol and DI/RO water

            Originally posted by d_striker View Post
            Good explanation. I assumed distilled water was less corrosive as that is what you're supposed to use in car radiators to minimize corrosion.
            When you add the glycol to the RO/DI water, it drops the resistance and is no longer reactive water. The solubility of the glycol acts as the minerals in the water. If you have it around, you can more accurately calculate your thermal transfer formulas because tap water and RO/DI water will be slightly different. The only reason I would use tap water in my chiller is if we didn't make RO/DI water in-plant already, because it's generally way more expensive.

            SECOND EDIT:

            I talked to the guy that helped us set it up and he said that we did indeed ONLY USE PURE DI/RO water and inhibitor and pure glycol. We could have used city water if the calcium hardness was BELOW 100ppm.
            Last edited by chronolite; 01-23-2014, 02:23 PM. Reason: Totally wrong.

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            • #7
              Hi,
              Remeber that your inhibited propylene glycol is circulating in your system day after day and to have a high quality fluid is of essential to keep you system running without any problems. Please also keep in mind that you should never mixe different glycol brands because their inhibitor package is different and it could jepordise your protection.
              I have copied some statements from Dow Chemicals engineering and operation guide but you will see similar or same recomendations from all other big suppliers of inhibited propylene glycol worldwide.

              Water used to dilute DOWFROST ( inhibited propylene glycol) fluids must meet certain minimum standards for purity. Impurities in dilution water can increase metal corrosion, aggravate pitting of cast iron and steel, reduce the effectiveness of corrosion inhibitors, increase inhibitor depletion rate, cause formation of scale and other deposits on heat transfer surfaces, and cause clogging of system components. To assure inhibitor effectiveness, the levels of chlorides and sulfates in water used to dilute DOWFROST fluids should be less than 25 ppm each. Total hardness should be less than 100 ppm expressed as ppm calcium carbonate (See Table 5). Distilled or deionized water is recommended.

              Table 5— Dilution Water
              Quality Requirements

              Impurity, Level
              Chlorides, 25 ppm, max
              Sulfates, 25 ppm, max
              Total Hardness, 100 ppm, max as CaCO3
              Note: 17.1 ppm = 1 grain

              To obtain maximum heat transfer efficiency while achieving adequate freeze protection, avoid using excess concentrations of DOWFROST fluids in water. Generally when the fluid is used for either freeze protection or secondary cooling, the specified concentration should yield a freeze point about 5°F (3°C) lower than the lowest anticipated temperature.

              For optimum corrosion protection, the concentration of DOWFROST fluid in water should provide at least 25–30% (by volume) glycol. If operation at lower concentrations is desired, consult your Dow technical service representative for information.

              DOWFROST and DOWFROST HD glycol-based coolants contain specially formulated industrial inhibitor packages that are effective in preventing corrosion of metals commonly used in HVAC, food processing, and process heat transfer equipment. These inhibitors prevent corrosion of metals in two ways. First, they passivate the surface of metals, reacting with the surface to prevent acids from attacking it. Unlike inhibitors used in some other fluids, Dow inhibitors perform this passivation process without fouling heat transfer surfaces. The inhibitors in automotive antifreeze, on the other hand, contain silicates that coat heat transfer surfaces with a thick silicate gel that reduces heat transfer. Second, the inhibitors in DOWFROST fluids buffer any acids formed as a result of glycol oxidation. All glycols produce organic acids as degradation products. This degradation is accelerated in the presence of oxygen and/or heat. Left in solution, such acids lower pH and contribute to corrosion. Properly formulated inhibitors such as those in
              DOWFROST fluids neutralize these acids.
              The presence of excessive amounts (>25 ppm) of contaminants such as chlorides, sulfates, and/or ammonia could contribute to system corrosion For example, excessive concentrations of chloride ions will result in the formation of iron chloride. With any available oxygen, iron chloride will react to form iron oxide, which is insoluble. The resulting deposition of precipitant forms an area where under-deposit corrosion can occur. This corrosion will be further accelerated by the presence of chlorides and cannot be eliminated through the use of a non-chromate-basedinhibitor. This underscores the importance of dilution water quality.

              It is also important to maintain your fluid and it is recommended that you send in a glycol sample annualy to your glycol supplier to have them check your fluid and get recomdations if you need to take action on anything. This is normally free charge if you have more than 250 gallons in your system.

              You can also check the glycol concentration yourself by using a refractometer.

              Testing your fluid’s pH level —
              Control of pH between 8 and 10 is important to minimize corrosion and glycol degradation. Using narrow range pH paper such as pHydrion Control paper with a 7.2 to 8.8 pH range is an easy and reliable way to
              read your pH level. A pH tester can also measure alkalinity or acidity of the fluid. The desirable pH range should fall between 8.0 and 10.0. Adjustments can be made by using a 50% solution of sodium hydroxide or potassium hydroxide if the pH is between 7.0 and 8.0. Any fluid with a pH below 7.0 should be replaced. An inexpensive pH tester is available from Misco Products. The accuracy of this instrument is +/- 0.5 pH.
              Also, you can quickly determine the condition of your fluid by examining its appearance and odor. Any drastic variation from the initial fluid specifications, such as a black or dark-gray color, presence of an oily layer, burnt odor, or any heavy sludge in the fluid may indicate the need for fluid replacement.

              To read the whole DowFrost propylene glycol engineering and operation guide you can use this link: http://www.dow.com/webapps/lit/litor...6.pdf&pdf=true

              Cheers!

              Dan Strömberg
              Cooling Market Segment Manager

              Georg Fischer LLC
              Phone: +1 714 368 4196
              Fax: +1 714 368 4197
              Mobile: +1 951 642 2339
              Dan.Stromberg@georgfischer.com

              GF Piping Systems
              2882 Dow Avenue, Tustin, CA. 92780
              United States
              GF Piping Systems is the leading flow solutions provider across the world. We enable the safe and sustainable transport of fluids. Our business is driven by maintaining industry-leading sustainability levels, innovating through digitally enabled solutions, and investing in a culture built on performance, learning, and caring.

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              • #8
                Thanks Dan.

                So my takeaway from your post is that it actually is better to use RO/DI water for less corrosion.

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                • #9
                  Originally posted by scmorgan View Post
                  Taking all the minerals out of the water makes it hungry for all other availible items, particuarly metals. Best explanation from a mate who is in water treatment.

                  I can get 'raw' glycol half the price of one premixed, so having the same issues when i need over 3000l in total of glycol. Trying to find the inhibitors now ...
                  You can get FDA ADPAC inhibitor from ChemWorld. 2 gallons treats 55 gallons of glycol. Make sure to get the FDA approved version.

                  Propylene Glycol Rust Inhibitor. Stop Corrosion today!. Prices from $15 per gallon. We sell to Everyone. Free Delivery. Order online or call 800-658-7716.

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                  • #10
                    Originally posted by d_striker View Post
                    I received the Chill & Flow chiller that I ordered from ProRefrigeration and am almost ready to fill it up and start pumping it through our system.

                    I purchased USP food grade, 99.9% pure propylene glycol from propylene glycol suppliers. I was planning on using my RO/DI water filter to mix with the glycol. Do I need to add any corrosion/rust inhibitors to my solution?
                    I wouldn't recommend you to mix the propylene glycol with corrosive inhibitors. It is pretty dangerous to be dealing with such material. Just buy proylene glycol with the corrosive agent added to it. That would be the safest option. I am aware that 99.9% pure propylene glycol of USP food grade is non-toxic but the corrosive agents are. Avoid such circumstances where you have to deal with chemicals and mostly the ones you yourself has to come in direct contact in. But I would like to share the corrosive agents that are usually added to propylene glycol and water mixture to avoid corrosion of the heating system or cooling system. The traditionnally used inhibitors are silicates and phosphates. American systems use both these inhibitors but european vehicles usually do not have phosphates but other inhibitors including silicates. But then japanese made systems use phosphates but not silicates. I am not sure which make is ProRefrigeration as I haven't looked into that. I am still new on the forum hence I am still finding my way. Please take care keeping the make in mind and your safety.

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