Document zQ9K7xXqwoJQZgyGyb7M2GkLg

American Society of Heating and Ventilating Engineers Guide, 1934 Table 5. Friction Heads (in Milinches) of Central Circular Diaphragm Orifices in Unions Diameter or Orifices (Inches) 2 Velocity or Water in Pipe in Inches per Second 3|4 6 |8 | 10 | 12 18 | 24 %-in. Pipe 36 0.25 0.30 0.35 0.40 0.45 0.50 0.55 1300 650 330 170 2900 1450 740 380 185 5000 2500 1300 660 330 155 75 11,300 5700 2900 1500 740 350 170 20,800 10,400 5200 2600 1300 620 300 32,000 16,000 8000 4000 2000 970 480 45,000 23,000 57,000 12,000 26,000 6800 13,000 2900 - 6500 1400 3200 700 1600 47.000 24.000 53,000 12,000 27,000 5700 13,000 2800 6400 0.35 0.40 0.45 0.50 0.55 0.60 0.65 900 2000 3500 460 1000 1800 270 570 1000 160 330 580 190 330 200 120 1 -in. Pipe- 7800 4000 2300 1400 750 440 260 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 21,000 12,000 7000 4200 2400 65,000 37,000 22,000 50.000 13,000 28.000 7400 17.000 4300 10.000 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 0.55 0.60 0.65 0.70 0 75 0 HO 0.85 850 1900 3300 600 1300 2300 400 850 1500 260 600 1100 180 400 760 300 540 200 380 l}4-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 7 607000 40,000 27,000 60,000 18,000 40,000 12,000 26,000 1%-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 2-in. Pipe 7400 3900 2200 1320 850 460 275 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 12,500 7900 4200 3100 38,000 23,000 49,000 14,000 30,000 8100 16,800 4400 8850 practically true in tne tests to determine me iussc u ucau ... - .....---------,, .... _ .. ducted by the Texas Engineering Experiment Station, and also in the tests to determine the losses of head in orifices in 4-in., 6>in.. and'12-in. pipe, conducted by the Engineering Experiment Station of the University of Illinois. (Bulletin 109, Table 6, p. 38, Davis and Jordan). 480 Chapter 33--Hot Water Heating Systems between 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. GRAVITY CIRCULATION For gravity circulation, the one-pipe system shown in Fig. 6 and the two-pipe direct return system shown in Fig. 7 are probably in most common use. The one-pipe system has the disadvantage that the radiator nearest the 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 481