"Furles" write:
I've also seen large, cylinders of liqiid gas, Nitrogen I think, on
street corners, chained to a pole of some sort, with the gas being
piped underground. I think this was being done by Verizon
(telephones), so pipe freezing doesn't seem likely. ...

I noticed this myself the last time I was in New York, and had a chance
to ask a Verizon technician about it. It's simple cooling; the gas
cools as it expands on leaving the cylinder. As I recall what the man
told me, that they do it if the underground electronics are found to be
overheating. One cylinder lasts about a week.

I didn't ask why they use nitrogen, because that was obvious. It won't
support combustion and thus helps suppress any fire that might start
due to the overheating, and it's relatively cheap.
--
Mark Brader | "It never occurred to me that a living person could be
Toronto | used as a blowtorch, but we admit human beings are a
| bit special, don't we?" --Hal Clement: STILL RIVER

My text in this article is in the public domain.