Q. Why do we not use Ethylene Glycol in the USA?
A. Great Question. We use pumped glycol energy recovery systems all the time here in the United States. Up until recently we have almost exclusively used Propylene Glycol. Ethylene Glycol had not even been a choice.
The biggest reason for this is that Ethylene Glycol is toxic. If you drink a couple of ounces, you die. During Prohibition this actually happened. People drank just about anything they could distill, including ethyl alcohol. People died, and people remembered that.
What the heck! The main ingredient in the vast majority of automotive antifreeze on the market today is ethylene glycol. It’s also in most of the wind shield washer fluids. We’re either dripping it on our garage floor or spraying it all over our windshields, so why not use ethylene glycol in our pumped glycol energy recovery systems?
Benefits of Ethylene Glycol Solutions:
- higher heat transfer coefficient
- better freeze point depression
- higher surface tension, less leaks
- about 10% more efficient than Propylene Glycol in pumped systems
Because Ethylene Glycol is toxic it is more closely regulated than Propylene Glycol. Still you have to spill hundreds of gallons before reporting. The Environmental Protection Agency has a reportable quantity (RQ) for spills of 5,000 pounds (539 gal.). That’s a huge spill.
Ironically, even though ethylene glycol is listed due to its toxicity, the environmental harm caused by the product contaminating an ecological area is less than propylene glycol because its decomposition rate is faster by half. Thereby having a far lower Biological Oxygen Demand (BOD) than propylene glycol. So Ethylene Glycol is actually greener.
Finally, it’s worthwhile to point out that our friends in Europe and Canada only use Ethylene Glycol in their energy run around loops. Propylene Glycol is not considered as an option.
At DAC Sales, we are using Ethylene Glycol in nearly all of the systems that we design with Konvekta here in the United States. Looks like it’s time for a change.
More questions on pumped glycol systems; askRick?
Great information from Konvekta: Ethylene vs. Propylene Glycol
Dow Chemical Paper: Ethylene vs. Propylene Glycol
Related Pumped Glycol Energy Recovery Blog Posts:
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Konvekta High Performance Heat Exchanger Coil
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