Principal external dimensions for interchangeable vertical in-line centrifugal pumps, 'U' Type, driven by close coupled electric motors. Metric flange requirements for pump inlet and outlet connections. Pressure and temperature ratings. Basic selection chart defining zone of operation in terms of quantity and differential head. Appendices on derivations of basic selection chart grid, change of speed. Selection charts for pumps operating at 1450, 1750 and 3500 rev/min.