Document 2JXvO0nkgO46O45G7XpeaVobN

American Society of Heating and Ventilating Engineers Guide, 1935 Table 5. Friction Heads (in Milinches) of Central Circular Diaphragm Orifices in Unions Dumetkb OF Velocitt of Water "in Pips in Inches pss Second ------- Orifices 3(Inches) 2 4| 6 j8 | 10 | 12 | 18 | 24 | 36 %,-in. Pipe 0.25 0.30 0.35 0.40 0.45 0,50 0.55 'Vv/' 0.35 0.40 0.45 0.50 0.55 0.60 0.65 1300 2900 650 1450 330 740 170- - 380 185 5000 2500 1300 "660 330 155 75 11.300 20,800 32,000 45,000 5700 10,400 16,000 23,000 57,000 2900 5200 8000 12,000 26,000 1500 " 2600` 4000' " '6800' 13,000 740 1300 2000 2900 6500 350 620 970 1400 3200 170 300 480 700 1600 47,000 24,000 53(flnr) 12,000 27ionrv 5700 13.01* 2800 6400 900 2000 3500 460 1000 1800 270 570 1000 160 330 580 190 330 200 120 7800 4000 2300 1400 750 440 260 1-in. Pipe 14,000 7200 4100 2300 1300 800 460 22,000 12,000 6400 3700 2200 1300 720 32,000 17,000 9300 5400 3000 1800 1100 )' 37,000 65,000 21,000 37,00012,000 22,000 7000 43,000 4200 7400 2400 4300 0.45 0.50 0.55 0.60 0.65 0.70 0.75 1000 660 430 280 190 2250 1450 950 630 420 285 190 4000 2600 1700 1100 750 510 330 1 Yi-in, Pipe 8900 5800 3800 2500 1700 1150 750 16,000 10,400 6800 4400 3000 2000 1300 25,000 16,400 10,500 6900 4700 3100 2100 36,000 23,000 15,000 10,000 6700 4500 3000 53,000 34,000 22,000 15,000 10,000 6700 60,000 40,000 27,000 18,000 12,000 0.55 0.60 0.65 0.70 0.75 0.80 0.85 850 1900 3300 600 1300 2300 400 850 1500 260 600 1100 180 400 760 300 540 200 380 1 yj-in. Pipe 7400 5400 3600 2600 1800 1200 860 13,000 8600 7200 4400 3000 2200 1600 21,000 16,800 10,400 7000 5000 3200 2300 30.000 21.000 14,000 10,000 7000 5000 3000 50.000 30.000 21,000 14,000 10,200 7800 53,000 39,000 28,000 19,000 45,000 13,000 30,000 0.70 0.80 0.90 1.00 1.10 1.20 1.30 890 1850 3500 470 975 1800 255 560 1000 160 340 610 214 375 195 7400 3900 2200 1320 850 460 275 S-in. Pipe 14,000 7400 4200 2520 1600 950 525 22,300 11,700 6500 4000 2500 1360 980 33,000 17,000 9500 5800 3700 1910 1375 -- ----- :---- 37,000 20,500 38,000 12,500 .23,000 49,000 7900 14,000 30,000 4200 8100 16,800 3100 4400 8850 Note.--The losses of head for the orifices in the lV$-in. and 2-in. pipe were calculated from those in the smaller pipesi the calculations being based on the assumption that, for any given velotity, the loss of head is a function of the ratio of the diameter of the pipe to that of the orifice. This had been found to be practically true in the tests to determine the losses of head in orifices in K-in., 1-in., and lj-i-in. pipe, con ducted by the Texas Engineering Experiment Station, and also in the tests to determine the losses of head in orifices in 4-in.. CUin.. and 12-in. pipe, conducted by the Engineering Experiment Station of the University of Ulinoia.(Butletin 109, Table 6, p. 38. Davis and Jordan). Chapter 33--Hot Water Heating Systems and Piping the calculated heat losses and the actual heat losses, and also smaller than the, average difference between the calculated radiator sizes and the nearest stock sizes selected. CRAVITY CIRCULATION For gravity ci.rc.ula.tion, the one-pipe system shown in Fig. 6 and the tiro-pipe direct return system shown in Fig. 7 are probably in most common use. . The one-pipe.system has the disadvantage that thejradiator nearest the Fig. 6. A One-Pipe Gravity Circulation System Fig. 7. A Two-Pipe Direct Return Gravity Circulation System boiler is the only one which receives water at approximately the tem perature at which it leaves the boiler. All other radiators receive cooler water and must be proportionally increased in size, so the total heating surface in the system is considerably larger than that in a corresponding two-pipe system. The pipe sizes in gravity circulation systems may be varied. As the pipe sizes are decreased, the temperature drop through the radiators, which produces circulation, is increased and it becomes necessary to increase the temperature of the water leaving the boiler so that the mean temperature in the radiator remains constant. For example, Fig. 8 shows 569