This action depletes the oxygen levels of the effected waterways, which can have devastating effects if the amount of glycol and rate of biodegradation are great enough.
Like ethylene glycol, propylene glycol is combined with water in variable concentrations to depress the freezing temperature of a working fluid in heat transfer applications. There are extremely few, if any, instances where propylene glycol would be chosen for its thermal performance. Propylene glycol is considered to be relatively safe for humans. While less toxic than ethylene glycol, propylene glycol can pose some environmental concerns. Propylene — like ethylene glycol — is broken down by aerobic means, but where ethylene takes approximately 10 to 30 days to biodegrade, propylene glycol does so in 20 to 30 days or more.
Still not sure which type of glycol is best for your application? Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. Portal del DMT. Retrieved Need someone who understands your language? They would not cause any harm to the cooling system, but it does slightly weaken the heat transfer. Both glycols can typically be expected to last twelve years longer. Both produce acids in the present of air.
Between the two ethylene glycol is a better heat transfer fluid than propylene glycol. Propylene glycol is less toxic and is considered when toxicity is a concern. Ethylene glycol solutions are normally preferred over Propylene Glycol because of their more desirable physical properties particularly at lower temperature. However, in certain applications involving possible contact of the coolant with foods or beverages, it is recommended to use propylene glycol.
Ethylene glycol solutions are normally considered as pumpable down to freezing points commonly encountered under ambient conditions. Propylene glycol solutions become considerably more viscous at low temperatures.
Additionally, propylene glycol that meets the specifications of the Food Chemicals Codex, 3rd edition, and the United States Pharmacopoeia. In summary, both products have pros and cons pertaining to quality, capacity and usage. Propylene glycol often is the product of choice when toxicity is an issue or if there is an immediate environmental concern.
However, if these concerns are not an issue, ethylene glycol can be considered due to its superior physical attributes. In either scenario, consider partnering with a reputable inhibited glycol manufacturer for optimal product support.
Abigail Houghton is an account manager with Houghton Chemical Corp. The Allston, Mass. This website requires certain cookies to work and uses other cookies to help you have the best experience.
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Learn More This website requires certain cookies to work and uses other cookies to help you have the best experience. Propylene Glycol Molecule. TABLE 2. The viscosity of ethylene glycol and propylene glycol is compared. Abigail Houghton, Houghton Chemical Corp.
Order Reprints. Hydronic fluids are heat transfer fluids composed of three key ingredients: Water, to provide heat transfer Ethylene or propylene glycol, to depress the freeze point of the fluid. A balanced inhibitor system, to protect common metals of construction.
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