# Why is there a giant tank of Nitrogen sitting outside my house? **URL:** \ **Category:** Factual Questions\ **Created:** [January 15, 2005, 8:48pm UTC](https://boards.straightdope.com/t/why-is-there-a-giant-tank-of-nitrogen-sitting-outside-my-house/284906 "2005-01-15T20:48:07Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![meowpossum](https://avatars.discourse-cdn.com/v4/letter/m/848f3c/32.png) [@meowpossum](https://boards.straightdope.com/u/meowpossum)\ **Post date:** [January 15, 2005, 8:48pm UTC](https://boards.straightdope.com/t/why-is-there-a-giant-tank-of-nitrogen-sitting-outside-my-house/284906/1 "2005-01-15T20:48:07Z")
A metal tank labeled “Nitrogen,” about four or five feet high and two feet in diameter, suddenly appeared on the grassy berm on my sidewalk. It was chained to a street sign this morning when I walked the dog. Why? Is this something the city or local utility company uses for some kind of infrastructure maintenance? I have never seen workers using giant nitrogen tanks for anything and there’s no sign of any work being done. On the other hand, who else would schlep an undoubtedly heavy tank of gas around town and then abandon it outside my house? ---
**Author:** ![pravnik](https://avatars.discourse-cdn.com/v4/letter/p/8edcca/32.png) [@pravnik](https://boards.straightdope.com/u/pravnik)\ **Post date:** [January 15, 2005, 8:52pm UTC](https://boards.straightdope.com/t/why-is-there-a-giant-tank-of-nitrogen-sitting-outside-my-house/284906/2 "2005-01-15T20:52:03Z")
Itr’s probably your local phone company. They use them to keep the phone lines dry. ---
**Author:** ![friedo](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@friedo](https://boards.straightdope.com/u/friedo)\ **Post date:** [January 15, 2005, 8:52pm UTC](https://boards.straightdope.com/t/why-is-there-a-giant-tank-of-nitrogen-sitting-outside-my-house/284906/3 "2005-01-15T20:52:59Z")
Those tanks are usually used to pump nitrogen around electical or phone lines, to cool them down and dry them off. If you look closely it’s probably got a hose going into a manhole somewhere. ---
**Author:** ![pravnik](https://avatars.discourse-cdn.com/v4/letter/p/8edcca/32.png) [@pravnik](https://boards.straightdope.com/u/pravnik)\ **Post date:** [January 15, 2005, 8:57pm UTC](https://boards.straightdope.com/t/why-is-there-a-giant-tank-of-nitrogen-sitting-outside-my-house/284906/4 "2005-01-15T20:57:03Z")
The reason you never see any workers dropping them off or using them is because the phone and electric companies employ elves to keep the lines dry. If you wait until after midnight and catch one you can make it give you free utilities to let it go. ---
**Author:** ![meowpossum](https://avatars.discourse-cdn.com/v4/letter/m/848f3c/32.png) [@meowpossum](https://boards.straightdope.com/u/meowpossum)\ **Post date:** [January 15, 2005, 9:10pm UTC](https://boards.straightdope.com/t/why-is-there-a-giant-tank-of-nitrogen-sitting-outside-my-house/284906/5 "2005-01-15T21:10:54Z")
OK, but. . . cool lines off and keep them dry? It’s 4° F outside and hasn’t rained in a week. I’m going to have to catch me one o’ them utility elves **plotnik** talks about just to pay the gas bill this month. ---
**Author:** ![meowpossum](https://avatars.discourse-cdn.com/v4/letter/m/848f3c/32.png) [@meowpossum](https://boards.straightdope.com/u/meowpossum)\ **Post date:** [January 15, 2005, 9:15pm UTC](https://boards.straightdope.com/t/why-is-there-a-giant-tank-of-nitrogen-sitting-outside-my-house/284906/6 "2005-01-15T21:15:47Z")
> [@meowpossum](#): > > one o’ them utility elves **plotnik** talks about just to pay the gas bill this month. D’oh! **pravnik** , not “plotnik.” I’m sorry – I shouldn’t try to type on two hours’ sleep. ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [January 15, 2005, 9:22pm UTC](https://boards.straightdope.com/t/why-is-there-a-giant-tank-of-nitrogen-sitting-outside-my-house/284906/7 "2005-01-15T21:22:00Z")
Dry nitrogen gas is used to displace moisture-laden air in pressurized communications cables after splicing or following new installation. Cooling has nothing whatever to do with it. The cables are normally pressurized with dry air from a central location, and this pressurized air helps keep out water. After a repair, the utility temporarily hooks up a canister of either dry nitrogen gas or a tank of liquid dry nitrogen to push out the humid air that has leaked in. ---
**Author:** ![ParentalAdvisory](https://avatars.discourse-cdn.com/v4/letter/p/53a042/32.png) [@ParentalAdvisory](https://boards.straightdope.com/u/ParentalAdvisory)\ **Post date:** [January 15, 2005, 10:20pm UTC](https://boards.straightdope.com/t/why-is-there-a-giant-tank-of-nitrogen-sitting-outside-my-house/284906/8 "2005-01-15T22:20:02Z")
That, or they’re drinking a lot of whine on the job, and need to keep their supplies fresh. ---
**Author:** ![FatBaldGuy](https://avatars.discourse-cdn.com/v4/letter/f/ecd19e/32.png) [@FatBaldGuy](https://boards.straightdope.com/u/FatBaldGuy)\ **Post date:** [January 16, 2005, 12:48am UTC](https://boards.straightdope.com/t/why-is-there-a-giant-tank-of-nitrogen-sitting-outside-my-house/284906/9 "2005-01-16T00:48:12Z")
> [@Q.E.D.](#): > > liquid dry nitrogen That sounds like an oxymoron if I ever heard one! ---
**Author:** ![Bosda\_Di\_Chi\_of\_Tricor](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bosda_di_chi_of_tricor/32/16845_2.png) [@Bosda\_Di\_Chi\_of\_Tricor](https://boards.straightdope.com/u/Bosda_Di_Chi_of_Tricor)\ **Post date:** [January 16, 2005, 2:07am UTC](https://boards.straightdope.com/t/why-is-there-a-giant-tank-of-nitrogen-sitting-outside-my-house/284906/10 "2005-01-16T02:07:20Z")
> [@pravnik](#): > > The reason you never see any workers dropping them off or using them is because the phone and electric companies employ elves to keep the lines dry. If you wait until after midnight and catch one you can make it give you free utilities to let it go. Silly **pravnik**! The phone company uses werewolves. It’s the pizza deliverymen that are elves. 🙂