… for pipes, boiler shells, tanks, vats or the like, including pressure-reducing valves and thermostatically …
Explanatory notes
… tanks, vats or the like to regulate the flow (for supply, discharge, etc.), of fluids (liquid, viscous or gaseous), … an aperture (e.g., gate, disc, ball, plug, needle or diaphragm). They may be operated by hand (by means of a key, …