On/off valve capable of drawing back fluid when closed

摘要

An OFF/OFF valve including a fluid passage formed in the valve body, and having a valve seat, a smaller diameter portion extending from the valve seat on a downstream side of the valve seat, and a larger diameter portion extending from the smaller diameter portion on a downstream side of the smaller diameter portion. A valve element is disposed so as to be movable between a position adjacent the valve seat and a position within the larger diameter portion. The valve element is driven by a valve element driving assembly. When the valve is closed, the valve element moves toward the valve seat. When the valve element moves within the smaller diameter portion, the fluid which has passed through the valve element is drawn back due to the pumping effect of the valve element before the valve element finally reaches the valve seat and the valve is completely closed.