Choke valve

Its purpose is to restrict the flow of air, thereby enriching the fuel-air mixture while starting the engine.

The term "choke" is applied to the carburetor's enrichment device even when it works by a totally different method.

Commonly, SU carburettors have "chokes" that work by lowering the fuel jet to a narrower part of the needle.

In the extraction of petroleum (and other heavy-duty fluid handling contexts), a choke valve (or "choke") is an adjustable flow limiter that is designed to operate at a large pressure drop, at a large flow rate, for a long time.

For highly erosive or corrosive fluids, chokes can be made of tungsten carbide or inconel.