Two types of pipes commonly found in Providence.
Top: Peter; Bottom: Ted Johnson
(Because the rest of Providence is off at law school or some crap.)
By Agenda Staff
I live in downtown Providence and have seen 5 or 6 of these pipes coming out of the sidewalk (photo attached). Do you know what they are? Since there's no subway here, it doesn't seem like an exhaust pipe, and the design is unusual … any ideas?
—Peter (doubleagentrecords.com)
The Agenda's crack(ed) research team sprang into action on this and found Michael Newman, Chief of the Plumbing Division at the Department of Inspection and Standards who was willing to explain the pipes' function.
While it's true that there is no subway here, there are definitely networks of basements, sub-basements and interconnected tunnels in the Lovecraftian depths of Providence.
These “vent pipes” are for active venting of underground utility tunnels, especially gas and common utility ducts (those that carry multiple utility channels).
A combination of factors and events cause or allow various kinds of vapors to collect and build up in these enclosed spaces, including gas line seepage, moisture condensation, catalytic gas emission from electrical conduits (caused by field effects on insulation materials), and off-gassing from containment and insulation materials. Besides the obvious risk of fire, utility workers are at risk from breathing these gases.
Passive venting is insufficient to avoid buildup to hazardous levels. Active venting by electrically operated air exchangers is used to maintain safe levels within the tunnels. These don't operate all the time, but you may sometimes notice them running if you're close to one of the pipes.
Each vent system has two concentric pipes: The top one expels unwanted vapors while the wider encircling one, lower down, draws in fresh(er) air to replace the expelled air. (Most of the unwanted vapors are lighter than air—this prevents drawing them back in through the intake. To enhance this, the lower intake ring also has a cap on top and draws air from underneath the cap, making it harder to draw in expelled air; this also prevents rainwater, snow, and ice from coming in through the intake.) Narrow-gauge wire caging across both prevents invasion by wildlife.
