Abstract: The invention comprises an elongated housing having a valve body reciprocal therein between predetermined limits of oscillation and the valve body includes a spherical valve member automatically shiftable between open and closed positions as the valve body is shifted between its limit positions. A tubular plug is provided and may be used to lock the tubular valve member in the open position and the valve body is yieldingly urged to the limit position in which the valve member is in the closed position. The valve body, however, is constructed in a manner whereby fluid flow through the housing in a first direction above a predetermined velocity will maintain the valve body in the other limit position with the valve member in its open position.