Document 3ejzgLnVVwnK5dwmNzLMRQyeJ

American Society of Heating and Ventilating Engineers Guide, 1925-26 boiler feed pumps drop off very rapidly for the smaller sizes of pumps and for low load conditions. For this reason centrifugal pumps are not usually employed for installations of less than 1000 boiler horsepower. Screw pumps may be used with good economy for small capacities. 122 -gv.-.. ; American Society of Heating and Ventilating Engineers Guide, 1925-26 Table 67. Screw Pumps Since the.capacity and pressure at which Screw Pumps will operate is almost infinite, we can only give some idea of their capacity. Efficiencies range from 60 per cent to 70 per cent. s SlZB .2 2J4 3 3X 3'A 4 5 5M 6 7 8 9 10 12 16 G. P. M. 2-15 10- 20 20- 50 40- 60 55- 100 85- 200 175- 275 200- 325 275- 475 300- 600 450- 750 700-1000 800-1400 1200-2100 1750-4200 Max. Rev. 1600 1600 1600 1600 1500 1400 1200 1200 1200 1000 875 720 700 600 425 Suction Inches 2 2 2'A 3 4 4 .5 5 6 8 8 10 12 ' 14 16 - Discharge Inches VA m 2A 2A 3 4 4 4 6 6 8 10 12 14 15 Table 68. Sizes, Revolutions per Min. Heads Pumped Against, Power Required and Boiler Horse Power for Several Commercial Sizes of Centri fugal Boiler Feed Pumps Size of Pump Inches 2 2'A 3 4 5 6 8 2 2^5 3 4 5 6 8 - 2 2^ 3 4 5 6 8 H. P. Pipe Sizes Inches Suction J Discharge Capacity Gallons per Min. ' Two Stage for 100 lb. Working Pressure 2^ 2 100 3 2A 150 43 225 54 400 65 620 86 900 10 8 . 1600 Three Stage for 150 lb. Working Pressure 2A 3 4 5 6. 8 10 . 2 100 2A . 150 3 225 4 400 5 620 6 900 8 . 1600 Four Stage for 250 lb. Working Pressure 2/4 2 100 3 2A 150 43 225 54 400 65 620 86 900 10 8 1600 123 Boiler H. P. Served Without of Safety 1450 2175 3262 5800 8990 13,000 23,000 1450 2175 3262 5800 8990 13,000 23,000 . 1450 2175 3262 5800 8990 13,000 23,000 i