ARTC-SVX013A-EN
67
The addition of glycol to water yields a solution with a
freezing point below that of water. This has led to the
extensive use of glycol-water solutions as cooling media at
temperatures appreciably below the freezing point of water.
Instead of having sharp freezing points, glycol-water
solutions become slushy during freezing. As the
temperature falls, the slush becomes more and more
viscous and finally fails to flow.
Table 25. Freeze and burst protection chart
Water/Glycol
Temperature
Freeze Protection Burst Protection
20 °F (-7 °C) 18% glycol mixture 12% glycol mixture
10 °F (-12 °C) 29% glycol mixture 20% glycol mixture
0 °F (-17.8 °C) 36% glycol mixture 24% glycol mixture
-10 °F (-23 °C) 42% glycol mixture 28% glycol mixture
-20 °F (-29 °C) 46% glycol mixture 30% glycol mixture
The precise concentration of glycol for a particular chiller is
affected by several key factors such as ambient
temperature extremes, entering and leaving water
temperatures, and chiller size. A chillers optimum glycol
concentration is modified by these considerations as
reflected in Table 24, p. 66. These capacity correction
factors are the best informed estimates for chiller with
copper evaporators. The percentages may vary depending
on the materials and alloys of the heat exchangers, total
surface area, the amount of present or future fouling, and
the brand of glycol used.
Figure 35. Water/Glycol concentration freezing points
(in degrees Fahrenheit)
Operating Procedures
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