I have an uncle who is the quintessential cynic, skeptic, pessimist, elitist and oh, did I mention he is also quite negative? He is extremely well read, so it puzzled me that with this bundle of character traits, he was not argumentative. We discussed this once, and his response, although a bit caustic, befit his character: "Brian, I never argue because you will find that most people don't know much about anything."
Wow. But that's my uncle.
I must say, however, that there is an extraordinary amount of misinformation - bits of facts are blended with plenty of fiction and fabrication. In reading various online websites and forums, much of the speculation and conjecture as to the raison d'etre for tanks of nitrogen on the streets of New York City is hilarious and hysterical. It took quite a bit of digging to get nearer to the bottom, but the process of reading was fun.
Areas of science like chemistry and physics are particularly mired in myth-information. Ionizing and non-ionizing radiation are conflated, as are chemicals with common elements but completely different chemistry and properties. Extrapolation goes wild too. For example, in reading about the street side nitrogen tanks, many were concerned that there was a warning against suffocation. However, this is not due to any toxicity, but would only occur if someone were in an enclosed area and the nitrogen were to displace the air and, hence, the oxygen. Many were alarmed at the prospect of nitrogen being released, but ambient air is already 78% nitrogen.
All the confusion, speculation and misinformation is compounded with the monumental mistrust of governmental agencies or corporations, so reading statements from Verizon does little to pacify. A source of information on matters of trivia, urban legends and myths is the Straight Dope, a syndicated question and answer column by Cecil Adams, published in The Chicago Reader since 1973. Collections were published in book form and are also archived on the Straight Dope website. Adams has a history of digging deep to research questions. I did some reading there, but did not get a completely satisfactory answer.
Because moisture can damage cables, Verizon uses nitrogen to dry out its voice and data cables. Nitrogen is delivered via a small rubber cable fed through a manhole cover. But even many of the technical explanations appear incomplete. Most say that nitrogen is used to keep the cables dry. So why are these tanks only used temporarily, and what happens when they are removed? I found a more complete explanation from a former Verizon technician:
Verizon pressurizes the cables to keep moisture out and air flows through them constantly. 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". 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.
We are overwhelmed with an onslaught of information and resources. The online world of cut and paste research along with the viral proliferation of data has added to the confusion as well as clarification. Digging through it and sorting it out is challenging and exhausting. Why work harder than the rest? Just select the items you prefer from the a la carte menu of facts and fiction, and offer your own meal of myth-information :)