Abstract: A compressed air-actuated pump includes a venturi nozzle to create a vacuum condition within a fluid-tight pump body to pump in a liquid or slurry. When a given level of liquid is pumped in, a control circuit closes a flexible sleeve of a pneumatically actuated pinch valve positioned in an exhaust passageway of the venturi nozzle. Upon closing of the pinch valve, the exhaust stream from the venturi nozzle is diverted into the pump body to create a pressurized condition therein whereby the liquid or slurry previously accumulated therein is pumped out. The pump also includes a pair of variable flow control valves for independently adjusting the flow rates of compressed air through the venturi nozzle in the vacuum, pump-in and in the pressurized, pump-out cycles. Solid state opto-electronic liquid level sensors or appropriate pneumatic, electric or electro-pneumatic timing devices are employed to signal the opening and closing of the pinch valve.