Why Is There Liquid Nitrogen On The Street Corner?

Any NYC hackers may have noticed something a bit odd this summer while taking a walk… Giant tanks of the Liquid Nitrogen have been popping up around the city.

There are hoses that go from the tanks to manholes. They’re releasing the liquid nitrogen somewhere… Are they freezing sewer alligators? Fighting the Teenage Mutant Ninja Turtles? Or perhaps, cooling our phone lines??

Luckily, we now have an answer. Popular Science writer [Rebecca Harrington] got to investigate it as part of her job. As it turns out, the liquid nitrogen is being used to pressurize the cables carrying our precious phone and internet service in NYC. The cables have a protective sheath covering them, but during construction and repairs, the steam build up in some of the sewers can be too much for them — so they use liquid nitrogen expanding into gas to supplement the pressurized cables in order to keep the them dry. As the liquid nitrogen boils away, it expands 175 times which helps keep moisture out of the cables.

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