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Antifreeze, the water-tamer
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Antifreeze tames water’s wild ways, making water a better coolant for engines. New chemistries have elevated cooling system service from a chore to a technology.
The modern era presents the technician with four kinds of antifreeze: EG, PG, OAT and HOAT. In place of the traditional green, coolants in new engines are blue, red, pink, orange and yellow. Using the wrong one, or mixing different kinds, can cause serious engine damage. Using the right antifreeze is critical, but keeping track of what goes where can produce world-class headaches.
EG vs. PG
Antifreeze has two basic parts — a freeze-blocker and an anti-corrosion additive package that’s about 5 percent by volume of the product you buy. Add equal parts water and antifreeze, and you have coolant. You can adjust this 50/50 mix as needed. More antifreeze gives a lower freezing point and higher boiling point. More water improves engine cooling efficiency.
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Ethylene glycol (EG) has been the standard antifreeze since the 1930s. It was, and is, cheap and effective — and also toxic. People, cats, dogs and wild animals have died after consuming sweet-tasting spilled antifreeze. Lower-toxicity antifreeze, based on propylene glycol (PG), has been around since the mid-1990s. PG can be toxic, but it takes a much larger dose to do damage than EG, and in fact, PG can be found in small doses in some foods and cosmetics.
PG may be the choice for your golf course, given the abundance of life forms on land and in the water. But check with the equipment maker before switching. Be aware you’ll need new equipment to check PG coolant. You can’t mix EG and PG antifreezes and accurately predict freeze protection. Disposal is still an issue.
Keeping out corrosion
Neither EG nor PG reduces water’s tendency to promote corrosion among dissimilar metals. That’s the job of the additive package, which provides:
- Alkaline agents to neutralize the acids that promote metal-to-metal corrosion
- “Sacrificial” metallic elements that are destroyed, saving the engine parts from damage
- Chemicals that coat metal surfaces to shield them from attack without blocking heat transfer
- Anti-foaming agents to counteract air bubbles that can damage water pumps and cause heat-transfer and pressure problems
These anti-corrosives contain metallic elements such as silicates, phosphates, borates and others. Silicate levels were increased when aluminum became common in cylinder heads and radiators. Silicates provide a thin protective skin on aluminum. But silicates can “drop out” when combined with other chemicals, forming blobs that block water flow.
Phosphates also protect aluminum, but they combine with calcium and other minerals in “hard” water to form a rock-like scale that blocks heat transfer and can plug radiators. You can use acids to dissolve the scale, but that threatens the metal. Borates cause other problems with other materials.
Traditionally, you resolved these issues with periodic flushing and refilling. This got rid of debris and gave you a fresh additive package. But old coolant is a pollutant, full of toxic chemicals and heavy metals. Since there’s nothing chemically wrong with used EG or PG, companies developed recycling systems that filtered out the crud and restored the additives. That reduced disposal issues, but not the problems from accidental spills.
A new approach
General Motors attacked these challenges in the mid-1990s with “Dex-Cool” original-equipment antifreeze. This uses “organic acid technology” (OAT) to fight corrosion. It eliminates the metallic elements. Because it doesn’t sacrifice itself to protect the engine, OAT antifreeze lasts much longer before it needs flushing and refilling.
Dex-Cool was tinted a bright color some see as orange, others see as pink. Other engine makers have since introduced “hybrid organic acid technology” (HOAT) antifreeze that contains some metallic anti-corrosives. They’ve adopted their own colors.
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Entire nations have gotten into the act. Europeans, with their hard water, tend to use no phosphates to avoid scale. The Japanese tend toward high phosphates with little or no silicates. The Koreans and Chinese have their own formulas. Equipment makers all sell their own branded antifreeze with their own specific formulations and colors. After-market antifreeze doesn’t follow any particular color code, and may or may not meet the needs of a particular cooling system.
Finding the right solution
This challenges equipment managers and technicians. One golf machinery maker uses three different engine makers. One specifies antifreeze with no phosphates, the second specifies no borates, while the third specifies Dex-Cool.
Grab the aspirin. It’s a rare service shop that will have the time, space and organization to keep track of coolant confusion. The simplest solution may be to work with reputable vendors and settle on “universal” antifreeze acceptable for all, or most, of your equipment. Try it for a full season on a select few machines. If it causes no harm, adopt that coolant for the whole fleet.
Then closely monitor the machines to make sure the coolant is staying clean and that you’re avoiding scale formation, silicate dropout, rapid acid formation and early signs of problems, like premature softening of hoses.
If you’ll pay attention to the basic needs of all those machines and the need to keep things clear with your staff, you can keep your cool.
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