Glycol FAQ

Glycol is a water-miscible organic compound in the alcohol family. It is commonly used for cooling in industrial and mechanical applications. Glycol is sometimes called antifreeze or a coolant. Though it acts similarly to a refrigerant, and someone may refer to glycol as a refrigerant, this statement is incorrect. Glycol cools solely through heat transfer in an exchanger; whereas, refrigerant uses an evaporation-condensation cycle to remove heat.

The most important role glycol plays in a process cooling system is to adjust the temperature range of the system. Without any glycol in the system, the water will freeze at the normal 32°F (0°C). In this case, the system ambient temperature can never go below this temperature. However, many systems need temperature flexibility as pipes travel outside and into unheated areas. Adding glycol to the water lowers the freezing point. The percent of glycol determines what the new freezing point will be.

A lower freezing point means process fluid can be kept at colder temperatures. A greater difference between medium temperatures allows for a faster heat transfer process. Heat always travels in the direction of higher temperature to lower temperature. When a coolant with a colder temperature is used, more of the energy can be transferred from the other fluid or process to the coolant.

Glycol often contains corrosion inhibitors which can help to prolong the life of components. Its main function is to enable a cooling system to operate at temperatures below the freezing point of water. Certain systems may require this lowered cooling for optimum performance.

Deciding on the perfect glycol-water mixture is critical to your chiller’s operation. You will need to consider factors such as ambient temperature, desired lowered temperature, and heat transfer rate. The best way to determine a percentage for your system is to talk to a Chase Cooling Systems Expert. As there can be adverse effects on the cooling system when using glycol, the glycol concentration should be limited only to what is required for freeze protection.

Yes. There are two types of glycol commonly used for process chillers: Propylene and Ethylene Glycol. These products vary on metrics such as performance, environmental factors, and general safety. The specific needs of your process will determine which glycol type is best for your system.

In general, propylene glycol is considered food grade and can be used in food and beverage operations. Most brewery applications use this type of glycol. Additional certifications such as United States Pharmacopeia (USP) stamp can be sought to ensure that any glycol in the mixture indeed is safe for consumers.

Glycol can be purchased from reputable vendors, including Chase Cooling Systems. When purchasing glycol, know the concentration you need and the concentration you are purchasing. Glycol comes in stock concentrates as well as in set blends. It can be ordered in 55 gal drums, 5 gal pails, or bulk 275 gal totes. Always make sure you are purchasing the appropriate grade glycol. Automotive anti-freeze should never be used in a chiller.

If you have purchased a ratio that is higher than what your system needs, do not panic. You can still use this blend. However, you will need to perform onsite mixing. This process will involve adding water to the blend. Only use filtered, distilled or reverse-osmosis water. General tap water often has minerals such as calcium that can affect the chiller. After mixing and filling the system, any air pockets will need to be removed to prevent system frothing in the chiller.

Copper or ABS piping remain industrial standards for system piping. PVC is also sometimes used. The most important thing to consider when setting up a new system, is that the piping is properly sized. An undersized pipe may accidentally increase the pressure and could risk the rest of the system. Whereas, an oversized pipe may lower overall efficiency. Glycol is not recommended with galvanized piping, as it may adversely react with Zinc.

Since many chillers are factory set for water only solutions, some minor adjustments may need to be made. Areas such as the evaporator, pump, and hot gas bypass valve may need adjustments. Glycol has a lower specific heat capacity and a lower heat transfer efficiency. These factors must be considering when designing for a particular system. A trained professional should be able to easily make the necessary changes. The addition of glycol also changes maintenance concerns, as the new element will need to be tested and maintained along with the mechanical elements of the machine.

If your system or atmosphere have the potential to go below 32°F (0°C), then a glycol-water mixture should be used. A chiller’s process fluid should never freeze, as this stops the chiller’s ability to do work, and could even cause mechanical damage. To prevent these problems, talk to an expert and discover the best glycol mixture for your system.