Why do the drains in new york smoke?

Question

Why do the drains in new york smoke?

Answer 1

The dont smoke, they steam. Because of the steam pipes underground.

Answer 2

Because their parents smoked.

Answer 3

NYC uses centralized steam distribution lines to provided heat and power in the densely built up areas.

Steam lines need blow off valves to release the liquid water that condenses and builds up in the steam lines. The valves are self regulating (not self maintaining). When water vapor builds up, they blow off the vapor. The vapor is very hot and under high pressure in the steam lines. When it is released, it turns to steam. The blow off valves were designed to release the steam into the air via the storm drains outlets.

The blow off valves are needed to release an expected amount of water vapor build up in the steam line. Liquid water in the steam line can lead to corrosion and worse a condition called water hammer. This is basically a liquid slug of water that hits a bend or other restriction in a pipe at high speeds and pressure and exceeds the pipes design capacity to take the load, causing a pipe failure. Steam lines operate under very high pressure.

Answer 4

Not smoke steam.