A pump comprising: a pump body having a substantially elliptically shaped side wall closed by two end walls, and a pair of internal plates adjacent each other and supported by the side wall to form two cavities within said pump body for containing fluids, each cavity having a height (h) and a radius (r), wherein a ratio of the radius (r) to the height (h) is greater than about 1.2; an actuator formed by the internal plates wherein one of the internal plates is operatively associated with a central portion (22 or 23) of the other internal plate and adapted to cause an oscillatory motion at a frequency ( f ) thereby generating radial pressure oscillations of the fluid within each of the cavities including at least one annular pressure node in response to a drive signal being applied to said actuator when in use; an isolator disposed between said actuator and the sidewall to reduce dampening of the oscillatory motion of the actuator; a first aperture extending through said actuator to enable the fluid to flow from one cavity to the other cavity, the first aperture located at approximately a centre of the actuator; a first valve disposed in said first aperture to control the flow of fluid through said first aperture; a second aperture extending through a first one of the end walls to enable the fluid to flow through the cavity adjacent the first one of the end walls, the second aperture located substantially at a centre of the first of the end walls; a second valve disposed in said second aperture to control the flow of fluid through said second aperture; and a third aperture extending through a second one of the end walls to enable the fluid to flow through the cavity adjacent the second one of the end walls, the third aperture located substantially at a centre of the second of the end walls; whereby fluids flow into one cavity and out the other cavity when in use. a pump body having a substantially elliptically shaped side wall closed by two end walls, and a pair of internal plates adjacent each other and supported by the side wall to form two cavities within said pump body for containing fluids, each cavity having a height (h) and a radius (r), wherein a ratio of the radius (r) to the height (h) is greater than about 1.2; an actuator formed by the internal plates wherein one of the internal plates is operatively associated with a central portion (22 or 23) of the other internal plate and adapted to cause an oscillatory motion at a frequency ( f ) thereby generating radial pressure oscillations of the fluid within each of the cavities including at least one annular pressure node in response to a drive signal being applied to said actuator when in use; an isolator disposed between said actuator and the sidewall to reduce dampening of the oscillatory motion of the actuator; a first aperture extending through said actuator to enable the fluid to flow from one cavity to the other cavity, the first aperture located at approximately a centre of the actuator; a first valve disposed in said first aperture to control the flow of fluid through said first aperture; a second aperture extending through a first one of the end walls to enable the fluid to flow through the cavity adjacent the first one of the end walls, the second aperture located substantially at a centre of the first of the end walls; a second valve disposed in said second aperture to control the flow of fluid through said second aperture; and a third aperture extending through a second one of the end walls to enable the fluid to flow through the cavity adjacent the second one of the end walls, the third aperture located substantially at a centre of the second of the end walls; whereby fluids flow into one cavity and out the other cavity when in use. <EOS>