In a valve, the combination comprises a valve body defining an annular seat, and porting at upstream and downstream sides of the seat; a valve operating handle and stem; a tubular part connected into the body and defining a first side opening facing toward one of the sides; a tubular stopper sleeve received within the tubular part and having an open end facing the seat; and a second side opening rotatable by the stem into and out of registration with the first side opening whereby flow through the valve and stopper sleeve is established when the second side opening registers with the first side opening, and flow through the valve is blanked when the second side opening is rotated out of registration with the first side opening.