Liquid Nitrogen Plumbing

Liquid nitrogen, commonly referred to simply as LN₂, is a compact and easily transported source of very dry nitrogen gas. Handled carefully, it is a safer source than pressuized gas.

It's a clear liquid that looks much like water and is slightly less dense — 0.807 g/mL or just 80.7% the density of water. It is, however, extremely cold. It boils at 77 K (–195° C or –321° F).

A Dewar, named for the Scottish physicist and chemist James Dewar, who invented it in 1892, is a large vacuum flask used to store liquid nitrogen for periods of days to a few weeks. A big one for scientific and industrial applications is often called a Dewar, while a small one for your coffee is often called a Thermos, generally speaking they're all vacuum flasks.

Drawing from U.S. Patent number 872,795 for the Thermos brand insulating flask.

A vacuum between the inner and outer walls minimizes heat transfer. A small fraction of the liquid nitrogen boils off, holding the body of the liquid at 77 K. Nitrogen expands by a factor of 1:694 going from the liquid to the gaseous phase, so the dewer must be unstoppered or, more likely stoppered with a pressure relief value.

Dewars of liquid nitrogen can solve problems associated with running telecommunication cables in moist environments. In other words, LN₂ can keep your wires (and fibres, and fibre repeaters) dry.

New York's Financial District is at the very southern tip of the island of Manhattan, in the narrow twisting streets of old Nieuw-Amsterdam. There are huge numbers of telecommunications lines running through a small area just a few meters above the water line, where the East River and the Hudson River join in New York Harbor.

So, in New York it is pretty common to see Dewars of liquid nitrogen sitting along the street. They're often chained to a streetlight pole. A small red rubber hose is duct-taped to the ground and disappears into a manhole cover.

Here you see two Dewar vacuum flasks of liquid nitrogen along New Street, leading toward the New York Stock Exchange. The NYSE is on the corner of New and Wall Streets, fronting on New. That's its columned front with the large American flag in the background.

There is a guard post just across the street, so these Dewars have 24/7 protection and aren't chained to anything.

These Dewar vacuum flasks of liquid nitrogen are on the sidewalk along Broadway where it crosses John Street.

You can see the frost built up on the top plumbing in the close up view.

60 Hudson Street is the former Western Union Building and was its headquarters until 1973. It is still a major world communications nexus.

It's a carrier hotel with over 100 telecommunications companies interchanging Internet traffic. Another major carrier hotel in Lower Manhattan is at 60 Broad Street, just off Wall Street.

Also, Tuckerton NJ and the surrounding area include the landing sites for a number of cables to Europe, the Caribbean, and South America.

Lots of telecommunications lines in a damp underground.

Lots of uses for very dry nitrogen gas!

Rose George's The Big Necessity: The Unmentionable World of Human Waste and Why It Matters is a fascinating description of sanitation conditions around the world. "2.6 billion people don't have sanitation. [....] Four in ten people have no access to any latrine, toilet, bucket, or box. [....] Poor sanitation, bad hygiene, and unsafe water — usually unsafe because it has fecal particles in it — cause one in ten of the world's illnesses. [....] Diarrhea — nearly 90 percent of which is caused by fecally contaminated food or water — kills a child every fifteen seconds. The number of children who have died from diarrhea in the last decade [1998-2008] exceeds the total number of people killed by armed conflict since the Second World War.

In September 2009, Morna Gregory and Sian James published a book titled Toilets of the World. It's pretty much the same theme that you find here — photographs and commentary on other people's plumbing.

The Porcelain God: A Social History of the Toilet, by Julie Horan, contends that civilization began with the toilet.

Toilet: Public Restrooms and the Politics of Sharing, edited by Laura Noren and Harvey Molotch, has essays by anthropologists, sociologists, and architects on the importance of the toilet, especially for urban dwellers.

Latrinae Et Foricae: Toilets in the Roman World describes the toilets of the Roman Empire from Iberia to Syria, and from North Africa to Hadrian's Wall in Britannia.

Toilets, Bathtubs, Sinks, and Sewers: A History of the Bathroom, explains the history of personal cleanliness and hygiene to children in grades 5-8.

If you're not bored yet, you might be interested in (or at least tolerate):

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