Nuclear safety level rising -down check valve

The utility model provides a nuclear safety level rising -down check valve, which comprises the following components: a valve body, valve clack and valve gap, the fixed valve rod that sets up in valve clack upper end, the cover is equipped with the spring on the valve rod, inside the opening of valve gap has the guiding hole, the valve rod stretches into in the guiding hole, an installation movable plate between the lower terminal surface of spring and valve clack, clearance fit between movable plate and the valve rod, have the external screw thread on its lateral wall, the interior screw -thread fit who sets up on external screw thread and the valve gap, can make it reciprocate for the valve rod when rotating the movable plate, the up end of spring sets up a fixed plate, the fixed plate joint is in the shaft shoulder department of valve rod, and fix on the valve rod through the fastener. The beneficial effects of the utility model are that: through the swivelling movement board for the movable plate reciprocates, thereby changes the decrement of spring, and then the pressure of adjusting valve when opening, makes valve application scope wider, makes things convenient for the customer to use.