Top 5 Antifreeze and Coolant Chemicals

The antifreeze or coolant agents lower the freezing point and increase the boiling point of water-based liquids to prevent overheating. In the automotive industry, antifreeze and coolant chemicals are used vastly to keep the radiators of the vehicles from freezing or overheating. They also protect engines from corrosion and also support heat transfer. Methanol, ethylene glycol, propylene glycol, glycerin(glycerol), and propylene glycol methyl ether(1-methoxy-2-hydroxyproline) are the most famous and popular antifreeze and coolant chemicals.

However, additives that reduce or inhibit the oxidation of these chemicals are what make coolants different from one another. Furthermore, compounds like phosphates, nitrites, silicates, and borates also help to prevent the engine and cooling system metal components from corrosion. In this article, we will review the most widely used chemicals in the antifreeze and coolant industry.

Top 5 Antifreeze and Coolant Chemicals

• Monoethylene Glycol

Monoethylene glycol is the most used chemical agent as an antifreeze, representing the base of a coolant. It was first introduced to the market in the 1930s as an alternative to Methanol that had been used as a coolant in the automotive industry. In the beginning, it was not known that it can oxidize, damage the engine, and decompose its components. To avoid this, additives or inhibitors were added to the MEF to form a homogenous mixture. Compared to Methanol, monoethylene glycol possesses a higher boiling point and a lower freezing point which made the new solution better for cold and warm weather conditions in automobiles. 

On the other hand, monoethylene glycol is highly toxic, especially if swallowed. Hence, handling and disposing of these types of coolants have to be done with extreme caution to avoid children and animals from getting into contact with the substance, considering that it has a bitter-sweet taste.

• Methanol

Methanol has chemical properties that lower the freezing point of a water-based liquid and increases its boiling point. Before the 1930s, methanol was the most popular antifreeze. It was effective in preventing the coolant from freezing and its low boiling point and low specific heat capacity led to significantly less cooling than water alone. However, the concentration of methanol reduces constantly over time due to its greater tendency to evaporate. These features make methanol a good candidate as an antifreeze in windshield washer fluid to keep the cleaning fluid from freezing. Methanol is also injected into natural gas pipelines as it lowers the freezing point of water during gas and oil transport.

• Propylene Glycol

Labeled as "non-toxic antifreeze", propylene glycol is considerably less toxic than monoethylene glycol. It is used as antifreeze where monoethylene glycol is considered to be inappropriate including in food-processing systems or water pipes in homes where incidental drinking could be possible. That is why the U.S. FDA permits propylene glycol to be added to a large number of processed foods such as ice cream, salad dressings, frozen custard, and baked goods. it is also commonly used as the main ingredient in the "e-liquid" used in electronic cigarettes. Propylene glycol can oxidize to lactic acid.

Propylene glycol should be replaced when its color gets red. When an aqueous solution of propylene glycol in a heating or cooling system changes, this shows that the iron in the system is corroding significantly. In the absence of inhibitors, propylene glycol reacts with oxygen and metal ions, producing various compounds including organic acids (e.g., acetic, oxalic, formic) that accelerate the corrosion of metals in the system. To use glycol solution, regular monitoring of color, inhibitor level, freeze protection, pH, specific gravity, and biological contamination is required.

• Glycerin(Glycerol)

Glycerin is another glycol that has been given serious consideration by the industry. Glycerin has a three-carbon molecule with an alcohol group attached to all three carbons. Where propylene glycol and ethylene glycol are diols, glycerin is a trial. Although Glycerin can be made synthetically, it is a large by-product of biofuel production. That is why Glycerin is considered one of the most environmentally friendly antifreeze chemicals. It reduces the freezing point of water and raises the boiling point considerably. 

Nowadays, glycerin is vastly available and because of such low toxicity, is used in hundreds of products such as lotions, gels, drinks, and food products. The price of glycerin fluctuates a bit but it is usually close to ethylene glycol; so it seems to be a noble, very low-toxic option for making safe coolants which is why many coolant manufacturers have been working on developing a glycerin-based coolant.

However, glycerin has its drawbacks as well. Glycerin does not decrease the freezing point of water as efficiently as ethylene glycol. For instance, at least a 60% glycerin concentration is required to get to the same efficiency as the 50% ethylene glycol formula. This 10 percent adds cost. In addition, glycerin is as viscous as honey, so it has to be shipped and stored in a heated tanker or diluted with water which means only pre-diluted coolants can be made, stored, and shipped, and having a concentrated antifreeze based on glycerin is impossible. Glycerin is also very bio-active, meaning that it is an ideal medium for growing all kinds of fungi, and bacteria. To avoid this problem, inhibitor agents must be added which means more cost.

• Propylene Glycol Methyl Ether

Propylene glycol methyl ether (PGME) or 1-methoxy-2-hydroxyproline is a clear colorless liquid with a sweet odor and a bitter taste. Like other chemicals that are used in this industry, Propylene glycol methyl ether reduces the freezing point of water and raises the boiling point, and also mixes easily in water which all makes it an ideal chemical for coolant, especially for diesel engines. It is also a solvent for cellulose, acrylics, stains, dyes, and inks.

Summary

An industrial coolant absorbs heat from the machine or engine and emits it through a radiator or other devices. Industrial coolants are also known as antifreeze liquids, which are usually a blend of Methanol, ethylene glycol, propylene glycol, glycerin(glycerol), or propylene glycol methyl ether with water mixed in different ratios. Anti-freeze mixtures are resistant to low and high temperatures. These liquids are concentrated products with some corrosion inhibitors and other additives.