APPARATUS FOR DETECTING OPENING AND CLOSING OF CHECK VALVE

摘要

Provided is an apparatus for detecting opening and closing of a check valve, which includes a magnetic field generator that generates a magnetic field forming a closed loop that begins at a first point in place on the outer circumferential surface at one side of a seat body portion, passes through a valve disc, and arrives at a second point in place on the outer circumferential surface at the other side of the seat body portion, in which the second point in place has a phase opposing that of the first point in place; and an opening and closing detector which detects change of a magnetic flux in the magnetic field.