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Water corrosion control

Does anybody have any kind of internet information describing why DI water is better to use in coolant mixtures such as propylene glycol/di water/inhibitor, rather than tap water. From my understanding, di water does not have the high calcium and phosphates levels that tap water has and thus prevents corrosion deposits.

Glenn Denby
chemical manufacturer - Winnipeg, Manitoba, Canada
2004

DI water is excellent for cooling but also very corrosive.

Todd Osmolski
- Charlotte, North Carolina, USA
2004

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2004

DI or RO water is often used for coolants and has several advantages. If the application has a lot of evaporation, then using purified water for make-up avoids a build-up of salts in the water, which in extreme cases can cause scaling and corrosion, or de-emulsification of the coolant. It also helps to avoid microbial problems from sulphate-reducing bacteria since there are virtually no sulphates in the water.

The one problem from the use of DI or RO water is that without and hardness, the water has a very high tendency to form foam with most coolant mixtures. For this reason, many people use tap water for the initial make-up and then purified water for any subsequent additions.

Lyle Kirman
consultant - Cleveland Heights, Ohio