Explanatory notes
… flow by opening or closing an aperture (e.g., gate, disc, ball, plug, needle or diaphragm). They may be operated by … in this heading. In general, taps, valves, etc., are of base metal or plastics, but those of other materials ( other … (18) Taps and cocks for fitting in the bung holes of casks, barrels, etc. (19) Taps for bottle filling machines, …