I’m currently working in The Big Apple (New York City), and scattered around on many corners are these gigantic tanks that apparently contain liquid nitrogen. From these tanks come a small rubber hose, which is run into the street, and usually down a nearby manhole cover. (What happens to them after that is unknown, and the source of my question.) There is usually nearby construction in/on/under the streets, mostly by Con Edison (Power) or Verizon (Telephone/communications/data).
Now, I realize that The Great Cecil (and company) is/are based in the City of the Big Shoulders (Chicago), but I would believe his influence reaches even back here. So, enlighten me.
What do they do with the nitrogen after it gets under the street? (I don’t think it’s being used to help high-temperature superconductors operate; does it have anything to do with the construction?)
Is this just a strictly New York City phenomena, or does it happen in other big cities, like Chicago?
Thanks very much for any edification you all can provide.
Just a WAG, but perhaps they’re using the nitrogen to provide an inert environment in the wiring vaults and such underground to prevent sewer gas (methane) or natual gas from getting in there and becoming an explosion hazard.
I do remember this question was asked and amply covered in a previous thread some months ago but I am not goint to try a search now. Looking for “nitrogen” in GQ should find it.
I used to work on cable pressure for a telco and I’m amazed they actually get away with putting out LN (Low Pressure Nitrogen) drums in NYC. One kid with a $5 pocket knife could take out the entire telephone system. Hope terrorists never figure out what those are.
as has been mentioned, it is in fact used to pressurize underground cables to keep out moisture. Each liquid cylinder (they’re not actually dewa flasks as they’re under prexssure) can last a couple of weeks, and is cheaper than an equivalent number of compressed gas cylinders. I used to work for a company that supplied these to companies such as Verizon, so I know first hand.
Yep, thanks muchly for the explanations, as well as the pointer to the previous discussion. I did actually try to search for “nitrogen” both on the site and here in the forums, but I only reviewed the titles of the first 200 forum entries (out of 641, probably now 642), so I didn’t get far enough back to find that other thread. Thanks again.