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Archive for May 31st, 2014

Dry Water

My first thought was that you can’t make this stuff up:

Dry Water - Pok RR Station

Dry Water – Pok RR Station

That’s taken through one of the windows over Track 3 at the Poughkeepsie railroad station, so it’s a bit blurrier than usual.

It turns out a “Dry Water” pipe delivers ordinary water, but normally contains pressurized air to prevent freezing. An intricate valve in a heated room balances air pressure in the pipe against the supply water pressure; when the air pressure drops, water flows through the valve to the outlet.

Normally, you’d use a Dry Water pipe in a fire suppression system, but it makes perfect sense for an outdoor hose bib (or whatever you call that quick disconnect fitting) on the top level of the Poughkeepsie Railroad Station.

There’s (almost certainly) an automatic drain valve that removes water from the dry pipe: otherwise, it’d remain full after use and pop the pipe during the next freeze.

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