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F ig . 3. V o l u m e . o f Air t h r o u g h O r if ic e s u n d e r V a c u u m % Chapter XVIII--Pumps and Traps for Heating and Ventilating Equipment The increase in pump capacity may be reduced if a static head above the pump suction is provided. When this static head is made equivalent to the absolute boiling pressure of the condensate (measured in feet of water) minus 12 ft., no increase in pump capacity is required. Such static Table 6. Correction Factors for Standard Centrifugal Pumps for Tempera tures of Condensate above 180 Deg. Fahr. at Pump Suction Deo. Fabr. 190 200 204 Factor 1.15 1.56 2.00 Note.--To use Table 6, multiply the quantity of condensate to be handled by the factor corresponding to the temperature of the condensate at the pump suction and select a pump suitable for the quantity thus found. suction head requirements may also be reduced about 50 per cent when special large suction inlets or special impellers are provided. Sufficient head in addition to the total head necessary to overcome static head, velocity head, pipe friction and- boiler pressure should be provided wherever condensate is to be returned direct to a boiler from the pump. Table 7. Duplex Piston Type Return Pumps with Receivers Standard Pressure Size of Pinup 3 X 2 X 3H 4MX2MX4 5MX3HX5 6X4X6 7KX5X6 Receiver Capacity Gallons 12 20 40 . 60 100 Sq. Ft. Direct Radiation 6000 10,500 19,500 30,000 45,000 Lb. Condensate per Hour 2000 3500 6500 11,000 15,000 Minimum Steam Pressure 50 40 35. 35 30 i}i X 2 X 4 5K X 2K X 5 6 X 2J4 X 6 6X3X6 6X3KX6 Low Pressure 12 6000 20 . 10,000. 40 120,000 40 180,000 60 290,000 2000 3500 4000 6000 9000 25 20 15 20 25 Table 8. Centrifugal Return Pumps with Receivers Size of Pump Discharge Inches i iH 2 Receiver Capacity Gallons 40 60 100 .Sq. Ft. Direct. Radiation 12,000 25,500 42,000 Lb. Condensate per Hour 4000 8500 .14,000 , H. P. to Drive i m 2 293 Total Head Ft. 25 50 50