This close coupled style bronze self-priming centrifugal pump is equipped with high quality ball bearings permanently filled with grease for maintenance free operation. The main shaft seal is a mechanical face type seal of proven reliability. Unlike positive displacement pumps centrifugal pumps have larger internal clearances as the pressure is generated by centrifugal force and high liquid velocity. These pumps can handle impurities in the liquid and the flow in the discharge line may be throttled or shut off without the need for a relief valve.