Water Treatment in Glycol-Filled Cooling Systems for Data Centers

As data centers grow in scale and density, efficient thermal management becomes increasingly critical. Many modern facilities are turning to closed-loop glycol cooling systems due to their stability, heat transfer efficiency, and resistance to freezing in low ambient temperatures. However, the presence of glycol doesn’t eliminate the need for water treatment—on the contrary, it introduces a new set of challenges that require precision and ongoing monitoring.

Glycol-based coolants—typically ethylene glycol or propylene glycol mixed with deionized or softened water—are widely used in liquid cooling loops to prevent freezing and improve temperature stability, especially in data centers with chillers or indirect evaporative cooling systems. These fluids circulate through heat exchangers or rear-door coolers to manage the temperature of server racks and equipment.

But glycol systems are not maintenance-free. Over time, glycol degrades, especially under thermal and oxidative stress, leading to the formation of organic acids. This causes a drop in pH, which in turn accelerates corrosion in metal components such as heat exchangers, pumps, and piping.

The importance of water treatment in glycol systems:

1. pH Control

Glycol degradation lowers the pH of the fluid, increasing the risk of corrosion, especially in mixed-metal systems (e.g., copper, steel, aluminum). Buffered inhibitors and pH-adjusting chemicals are added through dosing pumps to maintain pH in the optimal range (typically 8.5–10.5 for inhibited glycol solutions).

2. Corrosion Inhibition

Modern glycol formulations often include corrosion inhibitors, but these deplete over time. Routine monitoring is essential to verify inhibitor levels and adjust dosing as needed. Real-time sensors and water treatment controllers can automate this process, reducing human error.

3. Microbiological Control

Although closed systems are less susceptible to biological growth than open cooling towers, bacteria can still infiltrate through maintenance work or initial fill water. Some bacteria even feed on glycol compounds. Incorporating biocides in small, controlled quantities helps mitigate biofilm formation and preserve system efficiency.

4. Particulate Filtration & Fluid Clarity

Over time, systems can accumulate particulates from pipe corrosion, degraded glycol, or external contamination. Inline filtration combined with chemical dispersants ensures that the coolant remains clean and does not block narrow heat exchanger channels.

5. Freeze Protection

It’s critical to verify the glycol concentration to ensure freeze protection, especially in systems exposed to variable ambient temperatures. Refractometers or inline glycol sensors can help track this with high accuracy.

At Advantage Europe, we have the needed equipment to monitor and control the treatment of your glycol system.

Inline glycol concentration, LPR corrosion and pH measurements combined on our controllers show you the parameters of your cooling system.

Contact us for more info!