A valve assembly for filling containers with metered quantities of materials includes a valve body (2) having a chamber (2A) therein, the valve body having open-top and bottom ends with substantially smooth interior sidewalls defining the chamber. A valve element (8) for opening and closing the openable bottom end of the valve body is disposed in the chamber adjacent to the openable bottom end (11A). An actuator device (10), including a pair of air cylinders, provides for relative movement between a lower portion (11) of the valve body in which the openable bottom end is disposed and the valve element in order to open and close the openable bottom end. A concentric sleeve is telescopically connected to the bottom portion of the main valve body, and is reciprocably movable in response to actuation of the air cylinders to open and close the valve.