ANTI-BLOCKING VALVE APPARATUS

The specification discloses valve apparatus installable in pipe line systems, carrying rockdust for use in coal mines, and adapted to prevent blocking of the pipe lines by an accumulation of rockdust. The valve apparatus comprises a Y-pipe fitting and a valve section of the pinch valve type. A pair of screw-operated pinch valves control flow through the main section and branch section, respectively, of the Y-pipe fitting. A rotary disc blocks access to the screws for operating the pinch valves except when a screw is in vertical registry with a radial recess in the disc. Closing of the main pipe line downstream of the branch line prior to opening the branch line which is necessary in order to prevent blocking, is thus assured.