So one of the red rubber hoses connecting one of these liquid nitrogen tanks to the sewer tripped me the other night. I was simply making my way across William Street on Exchange place, like I normally do on a Wednesday evening, on my way to school and kapow! I went flying through the air and landed splat on the tar, just ahead of a slow moving SUV. Now I hurt so bad that a couple of people had to help me up, but more than anything I was bruised, shocked and embarrassed. I said I was fine and sat on the curb for a few minutes. When I realized I was having a problem standing up I stayed put for a few more minutes. A police van went by and I tried waving it down, they waved back at me.

Since I was going to be late for class I hightailed it to the subway. When I got to school I had a few extra minutes so I called 311. I figured if I was that bruised imagine if that hose tripped someone of frailty like an out of work, drunken stock broker. I told the operator what happened and she put me on hold a few times, seemingly ignorant of the tanks existence and then finally connected me with a, HOLD IT, 911 operator. I couldn't believe that although I was fine, the situation was termed hazardous and therefore the 311 people were obligated to connect me with 911. Again I was put on hold by 911, but now I was late for class and lost the call as I headed for the classroom downstairs.

So this is just a warning. Those tanks can be hazardous if you're in a hurry and like me, a little clumsy. The city or verizon or con ed or, whoever, should put some kind of barricades or notification, orange cones, something to indicate that there is a hose, not secured to the ground, up ahead and looking to trip you up.

splicingdan is cool. thanks!

I worked with these tanks for 16+ years as a Verizon technician. The tanks are safe!

The main reason for the tanks is this:

Inside of a common telephone cable exist thousands of copper wires with paper or pulp insulation. They are twisted into pairs (tip and ring) and bundled into groups of 100 pairs (4200 pairs is the largest). These bundles are tightly wrapped with various layers of protection called sheathing.

Verizon pressurizes the cables to keep moisture out and air flows through them constantly. But, the subterranean world below the streets of Manhattan are a brutal world for these cables. In particular, Con Edison's steam.

What happens is this; as the air flows through a section of cable that is being heated by a steam leak, it rapidly heats. When the heated air passes by the heated section it rapidly cools, which in turn creates condensation INSIDE of the cable. Condensation inside of a cable with paper or pulp insulated wires will cause service outages. Verizon calls this a "steam section" or a "steamer".

Here's where the tanks come into play.

The tanks are filled with liquid nitrogen, but Verizon uses the nitrogen in the form of gas because it is almost perfectly dry. This dry nitrogen is forced into the cable and through the section that is in trouble thereby absorbing the condensation in the process. At the next accessible point of the cable, beyond the steam section, a "bleeder" is placed to allow the moistened nitrogen to escape and not travel through the remaining length of the cable.

You're right, sj. I've never seen such a collection of ill-informed comments as I've seen here... Oh, wait, this is Gothamist, after all. Most of these people would flunk 6th grade science if they had to take it again. The nitrogen isn't compressed. It's in essentially a giant Thermos bottle. People like edEx point to Mr. Wizard, forgetting that he was dipping things into an open flask of liquid nitrogen, obviously not pressurized. Pressurized and liquified gases are two completely different things.

Sheesh it's just nitrogen (you guys do know of course that air is 78% nitrogen). Nitrogen must be cooled to extremely low temperatures to condense into a liquid and then the only way to keep it a liquid in a normal temperature setting is to keep it under pressure. So the frost and such on the outside of the tank is due to the extremely cold temperatures inside which causes the moisture in the outside air to condense and freeze on the outside of the tank.

If one did happen to suddenly rupture it would be a real problem for whoever was standing right next to it. The liquid nitrogen itself isn't really going to do anything to you but it's the temperature of the liquid that's an issue. If you managed to get doused with freshly released liquid nitrogen, "severe frostbite" would be an understatement.

However, if released it would boil off very quickly since normal ambient temperatures are way way above the boiling point of liquid nitrogen. The liquid wouldn't make it too far from the tank before boiling off.

I would suspect that worrying about these tanks is a complete waste of your time and energy. Pressure tanks are very robustly built and I bet they would survive some pretty severe blunt impacts (i.e. cars) pretty well. I wouldn't shoot at one with a rifle though. Handgun might be OK, but I'd only try it from a distance just in case.

I imagine that if you must worry, you should worry about something that might actually have a remote chance of killing or injuring you, such as that cab that's about to run you down while crossing the street. Anybody who's worried about these tanks exploding but who still smokes cigarettes has their priorities really screwed up in a statistical sense, given which one is far more likely to kill or disable you.

I think Gothamist should write an article about the hazard of all these metal objects, moving at high speeds in the city, carrying TANKS OF GASOLINE!! My god, they're in every vehicle! What if there's ever a car accident.....the whole city will go up in flames!

They've filled with PEOPLE!!! PEEEEEEEPOOOOOOLEEEE!!!!

You can light up all you want next to a liquid nitrogen tank, bklyngrrl. Nitrogen isn't flammable and it doesn't explode. If the tank says oxygen or hydrogen then it is best to avoid producing flames.

I'm going to have bumper stickers made up that say "Place Tongue Here" with an arrow pointing to the coldest part of the tank.

"the knobs on top aren't locked so anyone can mess with them."

The blog post you link to is misinformed. The valves may not be locked, but there is no way to disable the safety system via a valve.

There was a mishap at Texas A&M 4 years ago with a nitrogen tank. The tank failed because someone had welded the safety plugs.

I can't find any info about the Genex/Praxair incident that talks about why the failure occurred.

Those ARE scary. I always avoid lighting up my cigarette when standing next to one of those. Especially if I'm wearing a lot of polyester and hairspray.

I'm picturing a summertime scene of bums standing around one rubbing their hands and sweating like a reverse fire-in-an-oil-drum air conditioner.

It's pretty hysterical that you can't bring mouthwash or nailclippers on an airplane, but it's OK for Verizon to have these things sitting on street corners in Manhattan.

OMG iz Ironic!

The point is that if the Times hasn't seen fit to mention once in the last 158 years that a nitrogen tank exploded, let alone that one exploded and injured or killed someone. If that's the case I'd venture that the chance of one of these things actually hurting someone infinitesimally small. It is interesting to know why the tanks are around town and what the nitrogen is being used for, but they are way down on the lists of street dangers.

they're filled with maple syrup gas!

Even better...the knobs on top aren't locked so anyone can mess with them.

@cucarachita: I was just thinking about the stealing thing...how much would they go for do you think? Pawn shops? anyone??

Cha-Ching.

But the chances of a tank rupturing? So what if the NYT never mentions it, it could've occurred elsewhere. Where are the chemists when you need them?

Duh, it's for Terminator 2 emergencies in case the T1000 travels back in time looking for John Conner.

thank you and thank you for addressing this..... I've long wondered about it.

The tanks are outside and unguarded because they are remarkably safe. The chance of one of these tanks rupturing is tiny. A search of the NY Times archive since 1851 shows zero articles reporting a death from a nitrogen tank explosion.