Determine the specific speeds of the following single-stage pumps and specify the type of pump which probably be used for each. Pump a PO r.p.m. 1150 885 675 625 9.p.m. 3500 12000 20000 9000 Total Head (ft) 100 15 50 18 2. A six-stage pump delivers 1500 g.p.m. against a net pressure rise of 700 lb per square in. What is the specific speed if it rotates at 1750 r.p.m.? 3. It is desired to pump 2800 g.p.m. of water against a head of 175 ft. What approximate operating speed would give the best efficiency. Efficiency in Per Cent 100 90 80 70 60 50 Below 100 g.p.m. 40 500 Center of Rotation Over 10,000 g.p.m. # -3,000 to 10,000 g.p.m. 1 1,000 to 3,000 g. p.m. 500 to 1,000 g-p.m.t 200 to 500 g. p.m.. 100 to 200 g.p.m.. 1,000. 2,000 3,000 4,000 Values of Specific Speed ng. r.p.m. vg.p.m. H% I breg Francis Radial 10,000 15,000 Mixed Propeller Flow Courtesy Worthington Pump & Machinery Corp. Approximate relative impeller shapes and efficiencies as related to 1. specific speed. Center of Rotation