A locking device for a valve

摘要

A locking device of an air-operated normally-closed valve for a gas cylinder (10) includes a housing (21); a piston assembly (30) provided in the housing (21); a tapered axial member (32) having an annular outer tapered surface and positioned coaxially with the piston assembly axis; a lock nut (25) which is screw-engaged with the housing (21) and coaxial with the tapered axial member (32); an annular inner tapered surface formed on an inner peripheral surface of the lock nut (25) to correspond to the annular outer tapered surface; an intermediate cylinder member (21 h) positioned between the annular outer and inner tapered surfaces; and a lock piece (27) inserted into a radial through hole (26) and contacting the annular outer and inner tapered surfaces. The lock nut (25) can press the lock piece (27) against the annular outer tapered surface via the annular inner tapered surface to lock the piston assembly (30) by adjusting the lock nut (25) with respect to the housing (21).