VALVE DEVICE HAVING SAFETY FUNCTION

摘要

PROBLEM TO BE SOLVED: To reliably prohibit non-desired opening and closing operation of a valve element and besides being excellent in operability. SOLUTION: This valve device comprises a valve guide 29 coupled to a valve casting 23, a valve element 52 contained at the internal part of the valve guide, and a lock mechanism 61 to lock the valve element in a valve closing position or an opening position. The lock mechanism comprises: a lock cylinder 52 rotatably in a direction extending around the axis of the valve element; an operating element 63 removable inserted in the insertion hole 65 of the lock cylinder and rotated in a direction running around the axis of the valve element; a plurality of tumblers 72 limiting free rotation of the lock cylinder relative to the valve guide the retracted in the lock cylinder based on the shape or the side edge of the operating element when the operating element is inserted in the insertion hole of the lock cylinder; and a cam groove 57 converting rotation movement of the valve element into reciprocating movement in an axial direction when the valve element is rotated in a direction around an axis and selectively moving the valve element to a closing position or an opening position.