A two-cavity pump having a single valve in one cavity and a bidirectional valve in another cavity is disclosed. The pump has a side wall closed by two end walls for containing a fluid. An actuator is disposed between the two end walls and functions as a portion of a common end wall of the two cavities. The actuator causes an oscillatory motion of the common end walls to generate radial pressure oscillations of the fluid within both cavities. An isolator flexibly supports the actuator. The first cavity includes the single valve disposed in one of a first and second aperture in the end wall to enable fluid flow in one direction. The second cavity includes the bidirectional valve disposed in one of a third and fourth aperture in the end wall to enable fluid flow in both directions.