Document omB9KjgNGRmzpKqwXnN03dj4w

506 CHAPTER 21 1951 Guide Table 3. Heat-cabbytno Capacity of Type L Copfeb Toeing with Tempebatube Deop of 20 Deo* Nominal Tube Sizes f tn. to 4 in., and Friction 60 to 720 milinehes per foot.. (A -- Capacity, Mbh. B = Velocity, inches per second) (One milinch equals 0.001 in.) Nominal Tubs Sob, In. A HB A HB A HB A y. B A 1B A iy. B A 154 B A 2B A 2X B A 3B A 3>4 B A 4B Milimcb Friction Loss per Foot op Tubs 720 10 27 20 35 36 37 51 42 104 43 185 55 300 62 625 76 1130 90 1840 98 2750 110 3900 120 600 9 24 18 30 '30 84 46 38 94 45 169 51 270 57 560 68 1010 80 1650 90 2480 100 3505 108 480 8 21 16 25 26 30. 40 33 82 39 149 45 235 51 495 59 890 69 1450 80 2170 89 3100 96 360 6.8 18 13.5 21 22.1 24 34 27 70 34 125 39 200 43 420 - 51 750 58 1210 66 1840 75 2600 83 300 6.2 16.5 12 19 20 21 81 24 63 30 112 35 180 39 ' 375 47 6S0 49 1100 59 1650 66 2350 73 240 5.4 14 10.8 17 17A 19 28 21 56 25 100 30 160 35 335 42 600 47 980 52 1450 57 2090 63 180 150 4.6 4 13 11 98 15 13 15 13.1 17 15 23.2 20.5 19 17 47 42 22 19 84 75 25 22 134 120 30 25 280 250 36 32 500 450 42 37 820 740 47 42 1210 1100 51 45 1750 1580 55 49 120 90 3.6 3 10 8.5 76 12 10 118 9.9 13 11 18.1 15.3 14 12 37 32 17 14.5 66 56 19 17 105 90 22 19 200 1S8 27 22 895 335 26 650 550 36 30 980 820 40 35 1390 1180 44 37 75 28 8 5.4 9 9 10 13.9 11.5 28 13 50 15 81 17 170 20 305 23 490 27 740 30 1080 34 60 2.4 7 4.7 8 7.9 9 12.1 10 25 12 4' * 71 15 * 150 18 270 21 420 23 650 26 950 29 For other temperature drops the pipe capacities may be chanced correspondingly* - For example, with temperature drop of 30 deg the capacities shown in this table are to be multiplied by 1.5. spectively. These figures would also illustrate forced circulation if a pump dr circulator were shown in the return line at the boiler. One-pipe gravity systems require very precise design owing to the small circulating head available. Also, circulation in them is slow, and tem perature drop is large toward the end of the main, and consequently these systems are usually considered impractical. One-pipe forced, systems compared with gravity systems provide more rapid circulation, with consequent smaller. temperature drop in mains and more uniform water temperature in all radiators, and are therefore preferred. Special flow and return fittings are available for improving the circulation to risers. Two-pipe systems have separate flow and return mains. If the return main is direct as shown in Fig. 5 the radiator at the end of the system has Pi Fi Fi, il Fig. 4. One-Pipe System Fig. 5. A Two-Pipe Dibect Return System J: \ Fig. 6^ A Two-Pipe Reversed Return System Hot Water Heating Systems 507 Table 4. Friction (in Milinches) of Central Circular Diaphragm Orifices in Unions (One tnilinck equals 0.001 in.) Diameter or Vzlocitt or Water is Pipe in Inches pee Second OzmcsB (Inches) 2 * 4 | 6 | 8 | 10 j 12 j IS 3/t-in. Pipe 1 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 12,000 6800 2900 1400 700 57,000 26,000 13,000 6500 3200 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 Ip^-in. Pipe 8900 5800. 3800 2500 170) 1150 750 16,000 10,400 6800 4400 3000 2000 1300 25,000 36,000 16,400 23,000 10,500 15,000 6900 10,000 4700 6700 3100 . 4500 2100 3000 53,000 34,000 22,000 15,000 10,000 6700 60,000 40,000 27,000 60,000 18,000 40,000 12,000 26,000 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 V2-in. Pipe 7400 5400 3600 2600 1800 1200 860 13,000 21,000 8600 16,800 7200 10,400 4400 . 7000 3000 5000 2200 3200 1600 . 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 J. 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 . The tosses of head for the orifices in the 1 M-io* and 2-in. pipe were calculated, from those in the 8mailer pipes, the calculations being based on the assumption that, for any given velocity, the loss of bead If a *.untlon of the ratio of the diameter of the pipe to that of the orifice. This had been found to be *ke tests 10.determine the losses of head in orifices in 1-in., and lM-in: pipe, con- i.i <jrTr Eusiueering Experiment Station, and also in the tests to determine the losses of brad ri nr?!? and 12-in. pipe, conducted by the Engineering Experiment Station of the University Of Illinois, (BvUdin 109, Table 6. p. 38, Davis and Jordan).