Abstract: Connected to the suction pipe leading to a pump inlet is an air eliminator comprising a valve housing defining a chamber and having a first valve seat through which the suction pipe communicates with the chamber and a second valve seat through which the chamber communicates with atmosphere, the chamber increasing in cross-sectional area from the first seat toward the second seat. A ball valve is normally seated on the first seat to prevent air from entering the suction pipe but is displaceable to allow discharge of air under pressure from the suction pipe through the second seat while suspended by the force of the discharging air. The ball valve has a specific gravity less than the liquid, whereby liquid entering the chamber from the suction pipe floats the ball valve against the second seat to block the discharge of liquid.