Antifreeze

What is antifreeze and why do we need it in our radiators? Frankly living in a city that rarely gets freezing temperatures, it’s not that necessary – or is it? However, there are many parts of the world that absolutely need it.

Antifreeze was developed to stop what was a common problem with engines in cold climates. During colder months, when the temperatures drop down below freezing, the water in the engine’s cooling system would freeze solid. As water freezes, it expands into a solid (ice – once described as “negative thermal expansion”) and this would put pressure on the delicate piping in radiators, the hoses connecting the radiator to the engine and also the engine unit itself – potentially widening any flaws in the casting of the block or causing other issues.

When the engine was started, the block would heat up and this would melt the ice in the block and slowly melt the ice in the remainder of the cooling system – however that meant a pressure build up in the system that could cause a failure. The water pump would be the first to fail if it was iced up as most pumps in older cars were driven off the engine. With the impellers frozen solid, the shaft would simply twist and snap.

All this meant that winter driving put a greater strain on the engine and its ancillary components. Today the idea of antifreeze has been absorbed into a more common phrase: engine coolant. The engine cooling system is more complex than most people think. If you use plain old water, you have to deal with corrosion of the steel in the block and you run the risk of a build up of contaminants that would block the whole system.

Antifreeze was originally developed by mixing methanol with the water to allow for a lower freezing point. Methanol was also used in de-icer and as a fuel for racing cars however it is corrosive to aluminium, so that meant cars had to be tested to ensure that the block and components were protected.

Research to solve the corrosion problem resulted in ethylene glycol being used instead. This helped improve the low temperature properties however like methanol, it was highly dangerous to humans. Another big issue was that ethylene glycol could oxide into several different types of acids – again not a good mix with human skin! Interestingly, although ethylene glycol was first formulated in the 1850s, it didn’t get used in antifreeze until the mid 1920s. Prior to that it was used as an ingredient for dynamite!

There is an old story that it was discovered to have a lower freezing point after waste from a Union Carbide factory in West Virginia leaked into the Kanahwa River and it didn’t freeze over. The Kanahwa Valley was known as “Chemical Valley” as it was a source of natural resources that meant many chemical plants were built to manufacture explosives and even Agent Orange. There is even a town called Nitro – after the explosive: nitro-glycerene!

Further developments saw propylene glycol being used instead of ethylene glycol, which has been termed the “non-toxic” antifreeze, however should be called the “less toxic” antifreeze as it is still toxic!

The funny thing about antifreeze is that it is also anti-boil because it works at the upper end of the temperature spectrum too, raising the boiling point of the water in the cooling system. The ethylene and propylene glycols are especially good at raising the boiling point of the coolant system – which is a good reason why it is put into cars in hot climates and why it is no longer simply antifreeze!