Abstract: Disclosed is a valve having (A) a valve body with an aperture therethrough, a threaded tap crossing the aperture and opening to only one side of the valve body, (B) a tap screw having a head of larger diameter adopted to screw into the threaded tap, where the tap screw has a hole therethrough which aligns with the aperture when the valve is in an opened position and which is at a substantially right angle to said aperture when the valve is in a closed position, and (C) an o-ring fitted under the head of the tap screw which is compressed between the head and the valve body when the valve is in an opened or closed position.