Explanatory notes
… appliances, used on or in pipes, tanks, vats or the like to regulate the flow (for supply, discharge, etc.), of fluids … viscous or gaseous), or, in certain cases, of solids (e.g., sand). The heading includes such devices designed to … regulate the flow by opening or closing an aperture (e.g., gate, disc, ball, plug, needle or diaphragm). They may …