Document VjXRx5K3D21kYGknLaKo7ma4g

528 CHAPTER 22 1954 Guide Table 3. Heat-carrying Capacity of Type L Copfeb Tubing with Tempebature Drop of 20 Deg* Nominal Tube Sizes 1 in. to J) in., and Friction 60 to 720 milinches per foot. (A = Capacity, Mbh. B = Velocity, inches per second) (One milinch equals 0.00! in.) njr.......TTpyrnfm T.nas per Foot op Tube Nominal Tube Sue, In. 720 600 480 360 300 240 180 150 120 90 75 60 n H 1 :m m 2 :m 3 3tf :4 A B 8.9 23.6 7.8 20.8 7.0 18.6 5.9 15.7 5.4 14.4 4.7 12.5 3.9 10.4 3.6 9.6 3.1 8.2 2.7 ` 2.3 2.1 7.2 6.1 5.6 A B 16.7 27.6 15.0 24.8 13.0 21.5 11.2 18.5 10.0 . 8.7 ; 7.5 16.5 14.4 12.4 6.6 10.9 5.6 9.3 5.0 8.3 4.5 3.9 7.4 M A B 29.0 32.2 26.0 28.8 22.5 25.0 19.0 21.1 17.5 19.4 15.0 16.6 13.0 14.4 11.5 12.8 10.0 11.1 8.5 9.4 7.6 6.7 8.4 7.4 A B 43.5 34.6 39.0 31.1 34.5 27.5 29.0 23.1 26.5 21.1 23.0 19.6 18.3 15.6 17.5 13.9 15.0. 13.0 12.0 10.4 12.0 9.6 10.5 8.4 A 93 B .. 43 84 39 74 34 63 29 57 27 50 42.5 23 20 38 18 34 28.5 16 13 26 23 12 11 A B 160 145 128 107 49 45 39 33 97 3 85 26 73 22 65 20 57 48.5 18 15 44 39 14 12 A B 260 56 240 206 52 45 175 160 38. 35 140- 118 30 26 106 23 93 20 79 17 71 62 15 13 A B 560 70 510 64 450 56 380 : 340 47 42 300 37 250 . 225 31 28 195 24 170 21 150 133. 18 17 A B 1100 89 930 75 820 66 700 57 630 51 550 . 470 44 38 420 370 34 . 30 310 25 280 250 23 20 A B 1650 1500 1300 1100 . 94 85 74 62 990 56 860 49 730 41 650 37 565 32 480 27 430 375 24 21 A B 2500 105 2250 94 2000 84 1750 73 1500 63 1320 55 1100 46 1000 42 860 36 730 31 660 580 28 24 A B 3600 3200 116 103 2800 2400 90 77 2150 69 1900 61 1600 51 1440 46 1250 40 1150 37 950 840 31 27 For other temperature drops the pipe capacities by"^5"' For example, with temperature drop of 30 deg the capacities shown in this table are to be multiplied by .0. spectively. These figures would also illustrate forced circulation if a pump or 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 nza (03, [G3-. tbl Fig. 4. One-Pipe System . Fig. 5. A Two-Pipe Direct Return System Fig. 6. A Two-PirE Reversed Return System Hot Water Heating Systems 529 Table 4. Friction (in Milinches) of Central Circular Diaphragm Orifices in Unions (One milinch equals O-OOl in.) Diametxbop Obotces (Inches) Velocity ,o Wates in Pi?b in Inches peb Second 3 | 4 . | 6 | 8 | 10 | 12 | 18 | 24 j $8 ' M-in. Pipe 0.25 0.30 0.35 0.40 0.45 0.50 0.55 1300 2900 5000 11,300 20,800 32.000 45.000 650 1450 2500 330 740 1300 170 380 . 660 185 330 155 75 5700 10,400 16.000 23.000 57.000 2900 5200 8000 12.000 28.000 47.000 1500 740 350 170 2600 1300 620 300 4000 2000 970 480 .6800 2900 1400 700 13,000 6500 3200 1600 24.000 12.000 . 5700 2800 53,000. 27.000 13.000 6400 l-in- Pipe 0.35 0.40 0.45 ' 0.50 0.55 -/0.60 0.65 900 2000 460' 1000 270 570 160"' " 330 190 3500 ` 1800 1000 580 330 200 120 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 13,000 7400 4300 50.000 28.000 17.000 10.000 1%-in. Pipe 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 8900 5800 3800 2500 1700 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 18.000 12,000 60,000 40.000 26.000 0.55 0.60 0.65 0.70 0.75 0.80 0.85 1^2 in. Pipe 850 1900 3300 7400 13,000 21,000 30.000 600 1300 2300 5400 8600 16,800 21.000 50.000 400 260 180 850 1500 3600 7200 10,400 14.000 30.000 53.000 600 400 300 1100 760 540 ` 2600 1800 1200 4400 3000 2200 7000 . 5000 3200 10.000 7000 5000 21.000 14,000 10,200 39.000 28.000 19.000 45.000 200 380 860 1600 2300 3000 7800 13.000 30.000 2-in. Pipe 0.70 0.80 0.90 1.00 1.10 1.20 1.; 890 1850 470' 975 255 . 560 160.. : 340 214 3500 1800 1000 610 375' 195 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 14,000 8100 4400. 49.000 30.000 16.800 8850 . - --<= lusses oi Bead tor tne orifices in the lM-in. and 2-in. pipe were calculated from those in the Pipes, the calculations being based on the assumption that, for any given velocity, the loss of head function of the ratio of the diameter of the pipe to that of the orifice. This bad been found to be prac- wcauy true in the tests to determine the losses of bead in orifices in in., 1-in., and iK-in. pipe, conducted y the Texas Engineering Experiment Station, and also in the tests to determine the losses of head in ori- .... ,Q 4~in> 6-in,, and 12-in. pipe, conducted by the Engineering Experiment Station of the University of "not*. (Bulletin 109, Table 6, p. 38, Davis and Jordan).