Every engineer knows that the use of an industrial inhibited glycol and water mixture is recommended in most water chiller systems. Ethylene and propylene are two of the common types of glycols commonly used. What is Glycol? Glycol is used to prevent freezing of the process fluid and ensure consistent flow at the operating temperature in a chiller. Inhibited glycols are also used to prevent the formation of scale and corrosion. Inhibited glycols have the ability to do this without damaging other parts of the chiller containing metals such as brass, copper, steel, cast iron and aluminum. Water systems can be treated with inhibited glycol to protect algae and bacteria from growing in the system. If algae gets into a water system, it can degrade the fluid system performance.

Below are 5 basic tips for using glycol in water chillers:

Do Not Mix

Never mix glycol brands. Mixing different brands of glycol can result in precipitating out the solution. Mixing glycols can also gel and clog filters and prevent proper flow rates. If you need to switch types of glycol, you must first run a thorough flush and clean of the fluid system. Once the system is flushed of the old glycol it will be ok to start the new brand.


Never use automotive grade anti-freeze in your system. These types of glycols are not designed for industrial applications and can cause many different problems with heat transfer and fluid flow. Many automotive glycols contain silicate-based inhibitors that have been shown in chillers to coat heat ex changers, attack pump seals, and form a flow restricting gel inside the unit.

Remember The Environment

Always try to be kind to Mother Nature and remember to check your local environmental regulation state and local codes when selecting a process fluid. Certain areas may have specific environmental regulations concerning the use and disposal of glycol or other additives.


Ethylene glycol is still used for most standard industrial applications. Ethylene glycol is the standard heat-transfer fluid for most industrial applications. This type of glycol can be used in any application where a low-toxicity content is not required. This glycol has a moderate oral toxicity and should never be used in process chillers where fluid could possibly come in contact with water or food products.


Propylene glycol generally produces the same freeze protection and corrosion/algae prevention levels as ethylene glycol, but with a lower level of toxicity. Propylene glycol is much easier to dispose of than ethylene glycol, and is much safer to handle. Propylene glycol is mostly used in the food industry and in applications where operators may come in frequent contact with the fluid.

To learn more about glycol and basic chiller maintenance, visit our website at chillerservicenorthwest.com