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.
• 
  Misco Products Model #7084VP
• 
• 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.

Percentage of Glycol*

Percentage of Water

°F

°C

0

100

32

0

20

80

20

-6.7

25

75

15

-9.4

30

70

10

-12.2

35

65

3

-16.1

45

55

-15

-20.6

50

50

-20

-26.7