reducing pipe fitting

Webster's Dictionary (GCIDE)

Reducing \Re*du"cing\ (r?*d?"s?ng), a & n. from Reduce. [1913 Webster]

Reducing furnace (Metal.), a furnace for reducing ores.

Reducing pipe fitting, a pipe fitting, as a coupling, an elbow, a tee, etc., for connecting a large pipe with a smaller one.

Reducing valve, a device for automatically maintaining a diminished pressure of steam, air, gas, etc., in a pipe, or other receiver, which is fed from a boiler or pipe in which the pressure is higher than is desired in the receiver. [1913 Webster]