By Karlhahn - Own work, Public Domain,

Proper Use Of Propylene Glycol

  • Choosing the Proper Glycol
  • An inhibited propylene glycol such as “DowFrost” is best.
  • DowFrost contains special corrosion inhibitors for low system maintenance and better heat transfer compared to other glycols.
  • It also has a longer fluid life, up to 20 years in some cases.
  • Use of Uninhibited Glycol
  • Even through uninhibited glycols do lower the freeze point, they are often more corrosive than water.
  • The corrosion rate of ethylene glycol on iron, for example, is more than 2.5 times faster than plain water. On steel, it is 4.5 times faster.
  • Automotive Based Antifreeze
  • Automotive based antifreeze Should never be used!
  • Automotive antifreeze contains silicate based inhibitors, which are compatible with automotive components.
  • In an industrial application, the silicates will coat the heat transfer surfaces and reduce the cooling efficiency of the system.
  • Silicates can also significantly reduce the life of pump seals.
  • Sources of Inhibited Propylene Glycol
  • For a complete literature package, material, safety data sheets and purchasing information, contact the following: Dow Chemical 1-800-447-4369 (Canada 1-800-363-6250) Dowfrost inhibited propylene glycol.
  • Maintenance Responsibility
  • A refractometer should be used on a regular basis to determine the mixture strength according to freeze point.
  • Typical Refractometer
  • Misco Products Model #7084VP 1-800-358-1100
  • View from Insite a Refractometer
  • The coolant freeze point is indicated on the line between the dark and light areas on the scale. In this example, the freeze point is about -5°F to -6°F.
  • The freeze point temperature should be 25°F below the lowest required setpoint (see chart).
  • Water evaporates from the mixture, and if you continue to add a premixed solution, eventually you will have too much glycol.
  • It is necessary to add water or glycol to maintain proper freeze point temperature.
  • The refractometer pictured is accurate and easy to use for maintaining and checking for proper glycol levels.
Freeze Points for Water/Propylene Glycol Solutions
Percentage of Glycol*Percentage of Water°F°C
*Proplylene glycol.
Note: Glycol freeze point must be 25°F below lowest setpoint.

For More Information ... Contact Advantage Engineering, Inc at 317-887-0729

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