Glycol-based heat transfer fluids are used in many HVAC, industrial, and commercial closed loop systems to offer both freeze protection and heat transfer properties. To guarantee the best performance of the glycol system, additives are often included to glycol heat transfer fluids. This is done to prevent issues including corrosion, pH drops, system degradation, and fouling in the systems.
Glycol fluids are typically inhibited with pH buffers that provide reserve alkalinity to neutralize acidity. This extends the life of the alkalinity in a glycol closed system, which provides crucial corrosion resistance. These buffers often also function directly as corrosion inhibitors.
KEY INSIGHT: Reserve alkalinity is a measure of the concentration of alkaline components that can neutralize acids before the fluid becomes overly acidic.
Glycol products contain other specific corrosion inhibitors to directly protect against metal loss. They also may include deposit-control additives to keep system surfaces clean and facilitate the film-forming functions of the corrosion inhibitors.
There are a wide variety of buffering compounds and corrosion inhibitors available that can create and inhibit glycol products. In addition to preventing rust and corrosion, additives have many benefits in glycol systems. They can balance pH, prevent foam, control cavitation, and other important functions that will improve the quality of your process. These inhibitors are some that can be used to enhance your operations.
Dipotassium Phosphate is the most used inhibitor in the propylene glycol market. It is added to closed-loop water systems to protect the system metals from rust and corrosion. These metals include brass, copper, steel, and iron parts.
It can be used by itself or as part of a package with other inhibitors. When used by itself, it can be used as a food-grade corrosion inhibitor.
Molybdate is an excellent corrosion inhibitor and is effective in a variety of applications. It works by forming a protective film on internal surface of pipes and heat exchangers. It often costs more than other inhibitor but is known for its high quality.
Sodium Nitrite is another workhorse corrosion inhibitor and is specifically useful for aluminum alloys in glycol systems. It’s relatively low cost and proven effectiveness in glycol systems makes it an excellent glycol additive. It will break down in the presence of oxygen, so it is only effective in closed systems. This additive combined with others can be used to protect a wide range of metals.
Borate is often used as a buffer in glycol fluids and will help maintain pH even when glycol begins to breakdown. Maintaining pH is crucial for slowing the degradation process and maintaining a suitable environment to inhibit corrosion. It can also improve the thermal properties of glycol by raising the boiling point and lowering the freezing point of the glycol. This creates a more stable environment for the glycol solution across a range of temperatures.
KEY INSIGHT: The corrosion potential will increase as the pH drops.
Azoles are a family of chemicals which protect yellow metals, including copper and brass, from corrosion caused from byproducts. These byproducts, like acid, form as the glycol breaks down. Additionally, the usage of these additives can increase the system’s life. They cannot be used in food grade products.
Organic Inhibitors, like the innovative PDT Inhibitor found in Chem-Frost, consist of organic corrosion inhibitors or blends of inhibitors. In this, organics are blended with other commonly used inhibitors and buffers. They remain effective in high temperature applications where other inhibitors may break down. It can be used in a variety of applications including ventilation, heating, HVAC, and other closed-loop systems. This versatility allows for freeze and burst protection. It is also safe on aluminum substrates.
OYMI is a food grade material that inhibits corrosion on yellow metals. While most food-grade products must not be used on yellow metal substrates, DuBois food-grade products can be used in systems with copper in brass due to the innovative OYMI.
Oftentimes, specialized blends of the above inhibitors are used to maximize performance. While a boost in performance is expected when using a blend of inhibitors, it could come at higher costs.
These inhibitors are available for you to select and mix based on your unique application and purpose. Each with an exclusive formula, buffering and inhibitor packages in your operations will improve all aspects of your glycol systems. Ultimately this will save you time, energy, and money. to save you time, energy, and money.
Looking for more information about what inhibitors can help your systems the most? DuBois’ technical experts are ready to answer any questions you may have.
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