Vacuum priming system for centrifugal pumps

A self-priming pump system including a vacuum priming unit and a liquid pumping unit, the pumping unit having an engine driven centrifugal pump with an intake conduit, the priming unit having a vacuum column with an internal well chamber and a vacuum chamber above the well chamber with an interconnecting gas relief passage, the well chamber having liquid level sensors to detect the water level in the well chamber and activate a vacuum control valve connecting a vacuum pump to the vacuum chamber when the water level in the well chamber falls below a predetermined level, the control valve switching to seal the vacuum chamber and connect the vacuum pump to atmosphere when a predetermined level of water is detected in the well chamber.