vent pipe

noun Plumbing.

a pipe above a waste pipe or soil pipe that allows gas to escape from the system.

Origin of vent pipe

First recorded in 1855–60

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

It is indispensable that every acetylene apparatus shall be fitted with a safety-valve, or more correctly speaking a vent-pipe.
Acetylene, The Principles Of Its Generation And Use
F. H. Leeds
Typical simple forms of vent-pipe suitable for acetylene apparatus are shown in Fig. 7.
Acetylene, The Principles Of Its Generation And Use
F. H. Leeds
Nevertheless this form of vent-pipe produces a gurgling noise, and would be better for a trumpet-shaped mouth.
Acetylene, The Principles Of Its Generation And Use
F. H. Leeds
So tall a vent-pipe, however, seriously raises the centre of gravity of the bell and may make it top-heavy.
Acetylene, The Principles Of Its Generation And Use
F. H. Leeds
No water enters the vent-pipe from the holder, and therefore no gurgling or irregular pressure is produced.
Acetylene, The Principles Of Its Generation And Use
F. H. Leeds