10 Glycol Tips for Water Chiller Operators


The use of an industrial inhibited glycol and water mixture is recommended in most water chiller systems. Ethylene and Propylene are the two standard types of inhibited glycols commonly used.

The main job of glycol is to prevent freezing of the process fluid and ensure consistent flow at the operating temperature. Inhibited glycols will also prevent formation of scale and corrosion while protecting metals such as brass, copper, steel, cast iron and aluminum. Water systems treated with an inhibited glycol will also be protected from algae and bacteria that can grow and degrade the fluid system performance. This brief provides ten basic tips for glycol users in water chilling operations.

1. Don’t Mix Glycols

Do NOT mix different types or brand names of glycol. This can result in some inhibitors precipitating out of the solution. Mixing glycols will also gel and clog filters and prevent proper flow rates. If switching glycol types, it will be necessary to run a thorough flush and clean of the fluid system. Once that’s done, it’s okay to change over.

2. Don’t Use Automotive Grade Anti-Freeze

Do not use automotive grade anti-freeze in the chiller process. These types of glycols are not designed for industrial applications and may cause problems with heat transfer or fluid flow. Many automotive glycols contain silicate-based inhibitors that can coat heat exchangers, attack pump seals, or form a flow restricting gel.

3. Check Local Environmental Regulations

Check state and local codes when selecting the process fluid. Certain areas may have environmental regulations concerning the use and disposal of glycol or other additives.

4. Ethylene Glycol 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. Ethylene glycol has moderately acute oral toxicity and should not be used in processes where the fluid could come in contact with potable water, food, or beverage products.

5. Propylene Glycol for User-Contact Applications

Propylene glycol maintains generally the same freeze protection and corrosion/algae prevention levels as ethylene glycol – but has a lower level of toxicity. This type of glycol is more readily disposable than ethylene and safer to handle. Propylene glycol is commonly used in the food industry and in applications where the user may come in frequent contact with the fluid.

6. Difference Between Ethylene and Propylene Glycol

At very cold temperatures, propylene glycol become more viscous, changing the heat exchange rate slightly. Some chillers are designed for that compensation so that either glycol type can be used. Ethylene is more widely known due to its lower purchase price, making it more economically feasible for factories with significant purchasing volumes.

Koolant Koolers recommends propylene as its MSDS (Material Safety Data Sheet) handling is less rigorous, making it easier for facility maintenance staff if they ever need to fill or clean up a glycol spill. Please note that some U.S. states prohibit the use of ethylene glycol for environmental reasons.

7. Use Distilled or Reverse-Osmosis Water

Thought and planning should be dedicated to selecting the water to mix with glycol. Water should come from a good quality, filtered source meeting the requirements of the process machine manufacturer. Koolant Koolers recommends the use of distilled or reverse-osmosis water for the glycol/water mixture.

8. Beware De-ionized and City Water

De-ionized water can be used to fill the chiller process initially, but should not be maintained at a de-ionized state thereafter. Unless the chiller has been ordered and designed for use with water that is continually de-ionized, the fluid will actually attack certain metals within the chiller and cause damage to some components. Check with the chiller factory before using de-ionized water to check for compatibility.

Neither is the use of regular tap water recommended. Water from “the city” or “the ground” contains deposits and additives which can decrease component life and increase maintenance requirements.

9. Applications Drive Water/Glycol Mix Percentages

The location of the chiller and environmental concerns must be taken into account when selecting the proper mixture of glycol and water for the chiller process. A process located completely indoors, with no chance of freezing, will require less glycol than a system located outdoors where low temperatures can cause the fluid to freeze and piping to burst. Applications with a very low operating temperature (below 20ᵒ F) should use a glycol mixture equivalent to an outdoor system. After selecting the proper glycol and water types, use the following chart to determine the recommended mixture depending on the application and location of the process. The glycol percentage figures in the chart below will apply to any brand of ethylene or propylene glycol.

Application

Glycol %

Water %

Freeze Point

Indoor Chiller and Process

30

70

5ᵒ F / -15ᵒ C

Outdoor Chiller/Low Temperature

50

50

-35ᵒ F / -37ᵒ C

*Figures based on the performance of Koolant Koolers K-Kool-E brand of ethylene glycol.

10. Fluid Maintenance and Filtration

Maintaining clean process water and the proper glycol content will extend the life of the system and reduce costly down-time. If the chiller was not equipped with a fluid filter from the factory, it is highly recommended to install some sort of filtering system to remove unwanted dirt and debris.

 

For more information email us at: salesdept@dimplexthermal.com or visit www.koolantkoolers.com.