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Recent Changes in Coolant Technology and Testing Today’s coolant market is much more complex than it was when ALS Staveley Services first began its coolant testing program over 25 years ago. No longer can one think that “coolant is coolant” and just top off with whatever is on hand. There are a number of base fluids from which to choose and, from there, different inhibitor technologies to consider. There are four major base fluids from which to select: water, glycerin, ethylene glycol, and propylene glycol. While each has its place, superior freeze protection and cost considerations account for ethylene glycol being today’s manufacturer’s most popular choice. Cooling systems contain a wide range of metals (aluminum, copper, iron, lead, brass, solder), and any one of these base fluids will lead to corrosion of these metal components. As a result, inhibitors are added to all modern coolants in order to protect engines from corrosion. For years, conventional coolants dominated the market. These coolants used inorganic inhibitors to prevent corrosion. Phosphate, nitrite, and borate are added for iron protection; nitrate and silicate are added for aluminum protection; and azoles are added for copper and brass protection. There are a number of benefits to conventional coolant technology: • it is a proven technology However, the technology has its shortfalls. First, the inhibitors break down relatively quickly, putting the cooling system at risk. Because of this risk, manufacturers recommend the addition of supplemental coolant additive (SCA) at the initial fill. Thereafter, testing should be repeated and coolant added, if necessary, every 500 hours or 20,000 miles. In addition, when using conventional coolant, the cooling system needs to be completely drained, cleaned, and flushed every two years. These issues not only add to maintenance costs but significantly add to the waste disposal costs over the life of an engine. Extended life coolants (ELC) were introduced to combat the common conventional coolant issues. Extended life coolants replace the inorganic technology of conventional coolants with organic acid protection. ELCs are typically phosphate-, borate-, and silicate-free, getting their wear protection from a number of monobasic and dibasic carboxylic acids. These acids breakdown at a much slower rate than the inhibitors present in conventional coolants, providing ELC with a much longer life without the need of supplemental coolant additives. While ELCs are more expensive up front, decreased maintenance and waste disposal costs can result in reduced expenses over the long haul. It is important to keep in mind that extended life coolants are not interchangeable. Topping off with conventional coolant will deplete and decrease the effectiveness of the carboxylic acid protection. There are also many different carboxylic acids to choose from and, consequently, no two manufacturers have the same organic acid formulation. Mixing one ELC with another could lead to inhibitor dilution and protection issues. In 2007, we purchased advanced liquid chromatography equipment in order to stay current with changes in coolant technology. Working in close consultation with major coolant manufacturers, we quickly developed and validated a method for quantifying a number of organic acids and azoles. Our system works the same as a traditional liquid chromatography, separating the compounds present in a solution on the basis of their chemical properties so they can be properly identified and quantified. However, because we use the latest technology, this test that once took an hour can be completed in five minutes without sacrificing anything in the way of accuracy or precision. In fact, our method is so accurate and reliable that a global coolant manufacturer relies on our laboratories for quality control testing on all its coolants. In addition to being fast and accurate, our method is extremely adaptable. The method is validated to identify and quantify the organic acids found in the extended life coolant market today. In the future, if technology changes and different acids are introduced, with a little work and a few minor adjustments, we have the ability to begin testing for these compounds as well. Just recently, in response to one customer’s request, we began testing for denatonium benzoate by HPLC. While ethylene glycol is very toxic, it has a sweet taste, which can lead to accidental ingestion by children and animals. Denatonium benzoate, one of the bitterest compounds ever discovered, is widely used in the market today to prevent accidental poisoning. Our organic acid testing also focuses on in-service coolants. When extended life coolants were first introduced, they were advertised as being capable of lasting the life of the engine. While they do provide superior, longer lasting wear protection, our testing has shown that the organic acids do break down over time. This could lead to cylinder liner cavitation, and water pump and aluminum spacer deck corrosion. Testing the organic acid level at regular maintenance intervals can prevent these problems by ensuring that the coolant is still providing the necessary protection. As mentioned, when using extended life coolants, care must be taken to top off with the same extended life coolant every time. Our relationships with major coolant manufacturers, along with the additional testing we have performed over the last few years, have produced a lot of information about the organic acid components used by different manufacturers. Each manufacturer has its own formula, or acid “signature,” which our instrumentation can easily identify. While much of this information is proprietary, in many cases we are able to use it to identify the type of coolant a customer is using or if two or more extended life coolants have been mixed. Mixing two ELCs dilutes the inhibitors in both, and jeopardizes the system. Extended life coolants must never be diluted with conventional coolant. According to manufacturers, if an ELC is topped off with a conventional coolant to exceed 25% of the total volume of the cooling system, the coolant should be treated as conventional and flushed out at the next oil change. While a dilution of this kind might seem minor, the corrosion protection is seriously jeopardized through this practice. Using our advanced technology, along with other tests available in our standard testing package, we can determine if an ELC has been diluted in this manner and direct the customer to act accordingly. While extended life coolants clearly provide better, longer lasting protection than conventional coolants, a regular testing program remains a valuable tool that can save thousands of dollars while extending the life of your engine. |
July 2009