Document 3K71oK7K6gKE4yLJJKkDy57D

526 CHAPTER 22 1953 Guide Table 3. . Heat-carrying Capacity of Type L Copper Tubing ' : with Temperature Dhop op 20 Deg* Nominal Tube Sizes f in. to 4 in-, and Friction 60 to 720 milinches per foot. (A -- . Capacity, Mbh. B = Velocity, inches per second) (One milinch equals 0.001 in.) Nominal Tube Size, In. ` 720 Milinch Friction-Loss per Foot op Tube ' ,600 . 480 - 360. . 300 .240 180 150. 120 90 75 60 .h A * B. H A -. H A B H -A4 B 1 A B m A B A B A B .W A B A B 3*4 A B A B 8.9 23.6 16.7 27.6 29.0 32.2 43.5 34.6 93 -43 160 49 260 56 560 . 70 1100 89 1650 94 2500 105 3600 116 7.8 7.0 5.9 5.4 4.7 20.8 18.6. . 15.7 14.4 12.5 15.0 13.0 11.2 10:0 8.7 24.8 21.5. 18.5. 16.5 14.4 26.0 22:5 19.0 17.5 15.0 28.8 25.0 21.1 19.4 16.6 39.0 34.5 29.0 26.5 23.0 31.1 27.5 23.1 21.1 18.3 84 74 63 57 50 39 34 29 27 .23 145 128 107 97 85 45 39 33 30 26 240 206 175 160 140 52 45 38 35 30 510 450 380 340 300 64 - 56 . 47 - 42.. 37 930 820 700 630 550 - 75 66 57 51 44 1500 1300 1100 990 85 74 - 62. 56 860 49 2250 2000 1750 1500 1320 94 84 73 63 55 3200 2800 . 2400 2150 1900 103 90 77 69 61 3.9 10.4 7.5 12.4 13.0 14.4 19.615.6 42.5 20 73 22 118 26 250 31 470 38 730 41 1100 46 1600 51 3.6 3.1 2.7 2.3 9.6 8.2 7.2 6.1 6.6 5.6 ' ` 5!0 `4.5 10.9 , 9.3 ; 8.3 .7.4 11.5 10.0 -8.5' 7.6 12.8 11.1 9.4 8.4 17.5 15.0 13.0 12.6 13.9 12.0 10.4 9.6 38 34 28.5 26 18 16 13 12' 65 57 48.5 44 20 18' 15 14 106 93 79 71 23 20 17 15 225 195 170 : 150 28 .24 21 19 420' 370 310 280 34 30 25 23 650 565 480 430 37 32 27 24 1000 860 730 660 42 36 31 28 1440 1250 1150 46 40 37 950 31 2.1 5.6 3.9 6.4 6.7 7.4 10.5 8.4 23 11 39 12 62 13 133 17 250 20 375 21 580 24 840 27 . a For other temperature drops the pipe capacities may be changed 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 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 inains 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 Fig. 4. One-Pipe System Fig. 5. A Two-Pipe Direct Return System Fig. 6. A Two-Pipe Reversed Return System Hot Water Heating Systems 527- Table 4. Fri6tion (in Milinches) of Central Circular ` Diaphragm1 Orifices .in Unions (One milinch equals 0.001 in.) Diameter OF Velocity of Water is Pipe in Inches per Second ' ________ ____ . -. :i ! 3 i j 4 | 6 . | . 8 | . 10 j . i 18 1 (. : 0.25 0.30 0.35 0.40 0.45 0.50 0.55 1300 650 330 170 2900 1450 740 380 185 3/4-in. Pipe 5000 11,300 20.800 2500 5700. 10,400 1300 2900 5200 660 ' ; 1500 2600 330 740 1300 155 350 620 75 170 300 32,000 45,000 16,000 23,000 8000 12,000 4000 . 6800 2000. ,2900 970 1400 480 700 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 37,000 9300 21,000 5400 12,000 3000 7000 1800 4200 . 1100. 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 1 /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- 53,000 15,000 34,000 10,000 22,000 6700 15,000 4500 10,000 3000, 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 Vz-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 50,000 14,000 30,000 10,000 21,000 7000 14,000 5000 .10,200 3000 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 -The losses of head for the orifices in the l*4tn. and 2-in. pipe were calculated from those in the smaller pipes, the calculations being based on the assumption that, for any given velocity, the loss of bead 13 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 5*in.. 1-in., and l#-in. pipe, con ducted by the Texas Engineering Experiment Station, and also in the tests to determine the losses of brad onhces in 4-in.. 6-in., and 12-in. pipe, conducted by the Engineering Experiment Station of the University Illinois, (Bulletin 109. Table 6, p. 38, Davis and Jordan).