this post was submitted on 17 Jan 2024
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Mildly Interesting
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It’s actually too cold for salt to be reliable. Water fully saturated with salt freezes at ~-21/-6(c/f), so if it’s predictably getting colder than that, it’s a bad idea to use salt.
Edit: They add beet juice when it’s really cold, but otherwise, it looks like they use salt :(
It's salt but it's not sodium cloride. It's usually calcium cloride. That's usually good to -30/-34 F/C.
Interesting, I haven’t found anything to support that (but it’s weirdly difficult to research, so it could just be DDG not understanding what I’m looking for), do you have a source for that?
I found halite (unrefined sodium chloride) as the primary type of rock salt in the US. Wikipedia lists beer, molasses, and beet juice as possible alternatives for roads or glycol and sugar for airlines.
The EPA does list CaCl as an option, but notes that it’s both better for the environment and more expensive, so it’s reserved for vulnerable areas. I found this which doesn’t specify which they use, but gives an effective temperature range that sounds like NaCl for North Dakota.