What percentage of glycol/water do I need for my cooling system? | Dry Coolers Inc.

Dry Coolers Inc.

Industrial Process Cooling Systems

Dry Coolers, Inc.
575 South Glaspie Street
Oxford, MI 48371 USA


What percentage of glycol/water do I need for my cooling system?

For freeze protection, the required concentration of inhibited glycol fluid in a system depends on the operating conditions of the system and the lowest expected ambient temperature. For corrosion protection, it’s also important to consider the materials of construction, the age of the system and other variables. Your local glycol supplier representative can help you analyze the specific requirements for your system.

The table below shows the protection from freeze damage provided by various concentrations of DOWFROST glycol inhibited fluids. To determine the concentration required, select the lowest expected ambient temperature and decide whether the cooling system requires freeze protection to keep it pumpable, or burst protection to simply prevent damage from fluid expansion.

As a further measure of protection against dilution error, or unexpected cold temperatures, select a temperature that is at least 5°F colder than the lowest expected ambient temperature. If, for example, the lowest expected temperature is -15°F, select the line in the table below for -20°F. The table shows that at this temperature, a solution of 45% DOWFROST is required for freeze protection. A concentration of 30% to provide burst protection at this temperature.


  Freeze Protection Burst Protection
20 17% 11%
10 26% 18%
0 34% 23%
-10 41% 28%
-20 45% 30%
-30 49% 33%
-40 51% 35%
-50 53% 35%
-60 55% 35%