Patent ID: 7448408

Claim:
A check valve, comprising: a valve casing, the valve casing being formed with an inlet, a valve chest having a diameter larger than that of the inlet, and an outlet; an annular valve seat formed between the inlet and the valve chest; a valve element disposed within the valve chest to open and close the annular valve seat, wherein a recess is formed in the valve element on the inlet side; a valve stem projectingly provided on the inlet side of the valve element; a guide member with which an outer periphery of the valve stem is in sliding contact, the guide member provided at inner ends of ribs that project into the valve chest from an inner wall of the inlet, the recess in the valve element being formed to receive therein the ribs projecting to the valve chest side and also to receive the guide member, the inner ends of the ribs and the guide member being positioned within the valve chest; an outlet-side of the valve stem projectingly provided on the outlet side of the valve element; and an outlet-side guide member with which an outer periphery of the outlet-side valve stem is in sliding contact; characterized in that the length of the valve stem is equal to the distance between the valve inlet and the valve outlet in the valve casing; and the outlet-side of the valve stem projects out of the valve casing when said check valve is in the fully open position.