Protecting Your Chilled System This Winter
As winter temperatures descend, protecting your chilled water systems becomes a critical priority. Whether part of an air conditioning unit, an industrial chiller, or a process cooling system, failing to safeguard your system against freezing can result in costly damage and operational downtime. Here, we’ll discuss the risks of freezing temperatures and outline best practices to ensure your chilled system remains protected throughout the winter months.
The Danger of Freezing Temperatures
Chilled systems typically operate within a temperature range of 4°C to 12°C, with industrial setups occasionally requiring even lower temperatures. However, as temperatures drop below 4°C, water begins to behave in a unique and potentially damaging way - it expands as it approaches freezing.
When water freezes and transitions to ice, it expands by up to 9% in volume. This seemingly minor increase exerts enormous force, with pressures reaching up to 200 MPa (30,000 psi). To put this into perspective, these forces are strong enough to lift 13.5 tonnes—or the weight of a fully loaded 53-seater coach—for every square inch of frozen water.
If water freezes within a system's pipework, the resulting expansion can fracture even the strongest materials, including stainless steel and cast iron. The consequences of such damage include flooding, extensive repairs, and potential damage to surrounding infrastructure, which could disrupt operations for weeks.
Glycol: Your First Line of Defence
To protect your chilled system from freezing, maintaining the appropriate level of glycol-based antifreeze is essential. Glycol prevents water from freezing by lowering its freezing point, ensuring the system can continue to operate safely even during sub-zero temperatures.
In the UK, the use of glycol must comply with strict environmental and safety regulations. Ethylene glycol (MEG), while effective, is highly toxic and poses significant risks to health and the environment if mishandled. Due to its toxicity, MEG is not recommended for applications where it could come into contact with food or in healthcare settings, where patient susceptibility to harmful substances is a critical concern. In such cases, monopropylene glycol (MPG), which is a less toxic alternative, is commonly used. Always ensure that the glycol you select is compatible with your system and adheres to the relevant regulatory requirements.
Testing and Maintaining Your Glycol Levels
To verify the effectiveness of your antifreeze protection, regular testing of glycol concentration is essential. A refractometer is the preferred tool for this task, providing a precise measurement of the freezing point of your chilled water solution.
For most systems, a glycol concentration of 25% to 30% is sufficient to protect against freezing in temperatures as low as -10°C to -15°C. However, this can vary depending on your system's specific requirements and operating conditions.
A refractometer can be used to quickly & easily measure the level of glycol within your system as below:
Take a sample of the system’s fluid and ensure it is free from debris or contamination
Place a few drops of the fluid on the refractometer’s prism and close the cover.
Hold the refractometer up to light and read the freezing point indicated on the scale.
If your glycol concentration is too low, top up to maintain protection from freezing.
Additional Winter Precautions
Beyond maintaining proper glycol levels, here are additional steps to protect your chilled system this winter:
Insulate Pipework: Ensure all external pipework and components are adequately insulated to minimise heat loss and prevent freezing.
Check for Leaks: Regularly inspect your system for leaks that could dilute glycol concentrations or introduce air into the system, reducing its efficiency.
Monitor System Pressure: Freezing and thawing can cause fluctuations in system pressure. Regularly check and adjust to maintain optimal operating conditions.
Service Your System: Schedule a professional system service before winter to identify and address any vulnerabilities.
Conclusion
Protecting your chilled system this winter is not just a matter of maintaining operational efficiency - it’s a safeguard against significant damage and expense. By regularly testing your glycol levels, using a refractometer, and adhering to proper maintenance protocols, you can ensure your system remains resilient against the challenges of freezing temperatures.
If you need assistance with glycol top-ups, testing equipment, or winterisation services, Water Treatment Products is here to help. Contact us today to discuss how we can support your systems this winter.
