Glycol plays a vital role in closed-loop cooling systems, ensuring reliable performance by preventing freezing, minimizing corrosion, and optimizing heat transfer efficiency. However, improper glycol management can lead to system inefficiencies, equipment damage, and uncalled repairs. Without the right concentration, testing protocols, and maintenance strategies, glycol degradation can reduce system lifespan and increase operating costs.

At EAI Water, we take a proactive approach to glycol system maintenance. Ensuring proper glycol management is not just about adding fluid but also about precision, regular monitoring, and a deep understanding of the industrial water system. This guide outlines the best practices for maintaining glycol levels to keep your system running efficiently, minimizing downtime, and maximizing operational reliability.

Why Glycol is Essential for Closed-Loop Systems

Glycol serves as more than just a freeze protection agent for closed-loop systems; it is fundamental to maintaining system efficiency and longevity. Here’s why:

• Freeze Protection: Glycol lowers the freezing point of water, preventing ice formation that could rupture pipes and damage critical system components.
• Corrosion Inhibition: Inhibited glycol solutions, often containing a corrosion inhibitor, protect metal surfaces from rust, scale buildup, and degradation, reducing the risk of system wear.
• Thermal Stability: Glycol ensures consistent temperature readings and regulation, improving heat exchanger performance and preventing thermal fluctuations that impact efficiency.

Selecting the Right Glycol for Your System

The type of glycol used plays a crucial role in system performance and safety. Selecting the appropriate glycol depends on application requirements, environmental conditions, and regulatory considerations.

• Ethylene Glycol Based Solution – A highly efficient option commonly used in industrial and HVAC applications due to its superior ability to lower freezing points. Ethylene glycol, however, is toxic and unsuitable for food and beverage processing or environments where human contact may be a concern.
• Propylene Glycol Based Solution – A non-toxic alternative, often used in food processing and pharmaceutical industries, where safety is a priority. While slightly less efficient than ethylene glycol in heat transfer, it is the preferred choice when low toxicity is required.

Importance of Using Distilled or Deionized Water in Glycol Solutions

Using distilled or deionized (DI) water when mixing glycol in closed-loop systems is essential for preventing scale, corrosion, and inhibitor degradation. Tap water often contains minerals, salts, and impurities that can react with glycol, leading to scaling on heat transfer surfaces and accelerated corrosion of system components. DI or distilled water eliminates these contaminants, ensuring that the glycol mixture remains chemically stable and effective over time. However, fully deionized water can be too aggressive, so it’s important to follow manufacturer guidelines to maintain optimal water-to-glycol ratios.

What Are Glycol Meters and Why Accuracy Matters

While glycol does the heavy lifting in system protection, it’s the glycol meter that keeps your fluid in check. These tools are essential for measuring the concentration of glycol in water-based solutions—ensuring the system operates within optimal parameters.

What Is a Glycol Meter?

A glycol meter is a device used to measure the glycol concentration in HVAC, chiller, or industrial closed-loop systems. Maintaining the correct glycol-to-water ratio is essential for freeze protection, corrosion prevention, and fluid performance. Glycol meters allow operators to verify concentration levels quickly and accurately.

Types of Glycol Meters

• Refractometers – Use the refractive index of a sample to measure glycol concentration. Portable, quick, and ideal for field use.
• Hydrometers – Measure the fluid’s specific gravity, offering reliable results with a larger sample. Best for lab or shop environments.
• Digital Meters – Provide highly accurate readings with built-in or automatic temperature compensation, which corrects for ambient temperature fluctuations that might otherwise skew results. Some models also log data and integrate with system monitoring platforms.

Why Glycol Meter Accuracy Is Critical

• Prevents under or over-dilution of glycol, both of which can impair system performance
• Ensures effective freeze protection in cold-weather climates
• Validates corrosion inhibitor performance
• Extends system life and reduces repair costs
• Helps meet warranty and compliance requirements

Routine readings using calibrated glycol meters are one of the most effective ways to keep your closed-loop system running safely and efficiently.

Using Glycol Meters to Monitor System Health

Monitoring glycol levels is key to preserving system performance and catching problems before they escalate. Glycol concentrations should be tested every three to six months, with additional annual testing for corrosion inhibitors, pH, and conductivity.

Measurement Methods:

Using a Refractometer

A refractometer measures the refractive index of the fluid with just a few drops. It’s fast, portable, and excellent for spot-checking glycol concentration in the field.

Using a Hydrometer

A hydrometer measures the specific gravity of the fluid sample, giving a reliable indication of glycol concentration. Though more fragile, it’s ideal for lab testing or routine maintenance shops.

Tip: Always calibrate meters before use, and clean them after testing to ensure continued accuracy.

Maintaining Proper Glycol Concentration

For most systems, glycol concentration should be maintained between 30% and 50%. This range balances freeze protection, heat transfer efficiency, and fluid viscosity.

Why Concentration Matters

• Too Low (<30%) – Insufficient freeze protection, higher risk of pipe damage.
• Too High (>50%) – Reduced heat transfer, increased fluid viscosity, greater pump strain, and higher energy use.

Signs of Glycol Degradation & How to Address It

Even with regular monitoring, glycol degrades over time due to contamination, oxidation, and biological growth. Detecting degradation early helps avoid costly system failures.

Warning Signs of Glycol Degradation:

• Cloudy or discolored coolant – This often indicates particulate contamination, oxidation, or rust formation from corroded piping and system components.
• Unusual odors – A musty or foul smell could signal microbial contamination, which accelerates degradation and can lead to biofilm buildup in the system.
• Increased frequency of filter changes – Excess particulates, sludge, or scale deposits can clog filters, reducing flow and requiring frequent replacements.
• Decreased heat transfer efficiency – A higher Delta T (temperature difference) between the inlet and outlet suggests that the glycol solution is not transferring heat effectively, often due to contamination or breakdown of the fluid’s thermal properties.

Steps to Restore Glycol Integrity:

1. Flush & Replace – If glycol degradation is severe, a full system flush is necessary to remove contaminants, sludge, and degraded fluid before adding fresh glycol.
2. Use Inhibited Glycol – Switching to inhibited glycol formulations helps prevent future corrosion, oxidation, and microbial contamination, extending system lifespan.
3. Apply Biocides (if needed) – If microbial growth is detected, adding a biocide treatment effectively eliminates bacteria and biofilm, preventing further fluid breakdown.

Partnering with EAI Water for Expert Glycol Management

Maintaining glycol levels requires expert oversight, regular testing, and a strategic approach to fluid management. At EAI, we provide comprehensive glycol system solutions to ensure maximum system efficiency and reliability.

We offer:

• Expert consultation on selecting the right glycol type and concentration.
• Routine testing and analysis to detect early signs of degradation.
• Customized maintenance programs to optimize system longevity and performance.

Contact us today to keep your glycol system operating at peak efficiency.