Numbers of barrels (casks) transported or sold, or the volume that they represent.
Numbers of venturis in carburetion.
Volumes of crude oil pumped, stored, or sold (in bulk).
A solid disk or cylinder that fits inside a hollow cylinder, and moves under pressure (as in an engine) or displaces fluid (as in a pump)
A valve device in some brass instruments for changing the pitch
To move up and down or in and out like a piston.