Patent ID: 8297947

Claim:
A pump comprising: a pump body having a substantially cylindrical shaped cavity having a side wall closed by two end surfaces for containing a fluid, the cavity having a height (h) and a radius (r), wherein the ratio of the radius (r) to the height (h) is greater than about 1.2; an actuator operatively associated with a central portion of one end surface and adapted to cause an oscillatory motion of the end surface with an annular node between the centre of the end surface and the side wall when in use; an isolator operatively associated with a peripheral portion of the end surface to reduce dampening of the oscillatory motion; a first valve aperture disposed at any location in the cavity other than at the location of the annular node and extending through the pump body; a second valve aperture disposed at any location in the pump body other than the location of said first aperture and extending through the pump body; and, a flap valve disposed in at least one of said first valve aperture and second valve aperture to enable the fluid to flow through the cavity when in use, wherein the flap valve comprises: a first plate having apertures extending generally perpendicular through said first plate; a second plate having first apertures extending generally perpendicular through said second plate, the first apertures being substantially offset from the apertures of said first plate; a spacer disposed between said first plate and said second plate to form a cavity therebetween in fluid communication with the apertures of said first plate and the first apertures of said second plate; and, a flap disposed and moveable between said first plate and said second plate, said flap having apertures substantially offset from the apertures of said first plate and substantially aligned with the first apertures of said second plate; whereby said flap is motivated between said first and second plates in response to a change in direction of the differential pressure of the fluid across said flap valve.