Document e7OZD1Vvdkdym74y6pE7dEk9g

532 CHAPTER 22 1955 Guide Table 3. Heat-carrying Capacity of Type L Copper Tubing with Temperature Dbop of 20 Deg* Nominal Tube Sizes f in. to 4 in., and Friction BO to 7BO milinches per foot. (A. = Capacity, Mbh. B = Velocity, inches per second)._(One milinch equals 0.001 in.) Nominal Tube Size, In. 720 . 600 Milinch Friction Loss pbb Foot op Tube 480 360 300 240 180 150 120 90 75 60 H A 8.9 7.8 7.0. 5.9 5.4 ' 4.7 3.9 3.6 3.1 2.7 2.3 2.1 B 23.6 20.8 18.6 15.7 14.4 12.5 10.4 9.6 8.2 7.2 6.1 5.6 A 16.7 15.0 13.0 11.2 10.0 8.7 7.5 6.6 5.6 5.0 4.5 3.9 H B 27.6 24.8 21.5 18.5 16.5 14.4 12.4 10.9 9.3 8.3 7.4 6.4 H A B 29.0 26.0 22.5 19.0 17.5 15.0 13.0 11.5 10.0 8.5 7.6 6.7 32.2 28.8 25.0 21.1 19.4 16.6 14.4 12.8 11.1 9.4 8.4 7.4 A 43.5 39.0 34.5 29.0 26.5 23.0 19.6 17.5 15.0 13.0 12.0 10.5 H B 34.6 31.1 27.5 23.1 21.1 18.3 15.6 13.9 12.0 10.4 9.6 8.4 A B 93 84 74 63 :57 50 42.5 38 34 28.5 26 23 43 39 34 29 27 23 20 18 16 13 12 11 A 160 145 128 107 97 85 73 - 65 57 48.5 44 39 B 49 45 39 33 30 26 22 ... 20 18 15 14 . 12 iyt A B 260 240 206 175 160 140 118 106 93 79 56 52 45 38. 35 30 26- 23 . 20 -17 71 62 15 13 A B 560 70 510 64 450 56 380 47 340 .42 300 37 250 31 225 195 28' 24 170 21 150 133 19 17 2H :A B 1100 : 930 89 75 820 700 66 ^ 57 630 51 550 44 470 38 420 34 370 30 310 25 280 250 23 20 ' A;. 1650 1500 1300 1100 990 860 730 650 565 . 480 430 375 B 94 85 74 62 56 49 41 37 32 27 24 3>4 A B 2500 2250 2000 1760 1500 ,.1320 1100 1000 ' 105 94 84 73 63.. . 55 46 42 860 36 730 31 660 580 28 24 61. A 3600 3200 2800 2400 .2150 1900 1600 1440 1250 1150 950 840 B 116 103 90 77 69 : 51 46 40 37 31 ' * 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 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 Pi P P P P PiSB of ' " : 0J GJ-! Fig. 4. One-Pipe System Fig. 5. A Two-Pipe Direct Return System Fig. 6. A Two-Pf^ Reversed Return System Hot Water Heating Systems 533 Table 4. Friction (in Milinches) of Central Circular Diaphragm Orifices in Unions (One milinch equals 0.001 in.) Diameter of Orifices (Inches) Velocity of Water in Pipe in Inches per Second 2 !3 ! > 1 8 r io ! .2 18 24 %-in. Pipe 36 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 5700 10,400 16,000 23,000 57,000 330 740 1300 2900 5200 8000 12,000 26,000 47,000 170 380 660' 1500 2600 4000 6800 13,000 24,000 53,000 185 330 740 1300 2000 2900 6500 12,000 27,000 155 350 620 970 1400 3200 5700 13,000 75 . 170 300 480 700 1600 2800 6400 1-in. Pipe 0.35 0.40 0.45 0.50 0.55 0.60 0.45 0.50 0.55 0.60 0.65 0.70 Q.75 900 460 270 160 1000 660 430 280 190 2000 1000 1 570 330 190 3500 1800 1000 580 330 200 120 7800 - 4000 2300 1400 750 440 260 14,000 22,000 32,000 7200 : 12,000. .17*000 37,000 4100 6400- 9300 21,000 23001 3700 -. 5400' 12,000 1300 2200 - 3000- 7000 800' 1300 1800 4200 460 720 1100 2400 - .65,000 37,000 22,000 50,000 13,000 -28;000 7400 17,000 4300 10,000 lii-in. Pipe 2250 4000 1450 2600 950 1700 630 1100 420 750 285 510 190 330 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 60,000 40,000 26,000 0.55 0.60 0.65 0.70 0.75 0.80 0.85 lxA'in. Pipe 850 1900 3300 600 1300 2300 400 850 1500 260 600 1100 180 400 760 300 540 200 380 7400 5400 3800 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 13,000 45.000 30.000 2-in. Pipe 0.70 890 1850 3500 7400 14,000 22,300 33,000 0.80 0.% 1.00 470 975 1800 3900 7400 11,700 17,000 37,000 255 560 1000 2200 4200 6500 9500 20,500 38,000 160 340 610 1320 2520 4000 5800 12,500 23,000 49,000 1.10 1-20 214 375 195 850 1600 2500 3700 7900 14,000 30,000 460 950 1360 1910 4200 8100 16,800 1.30 275 525 980 1375 3100 4400 8850 ^^k'^The losses of head for the orifices in the lJ4-in. and 2-in. pipe were calculated from-those'in the ia a f P?Pes' the calculations being based on the assumption that, for any given velocity, the loss Of head ^.unction of the ratio of the diameter of the pipe to that of the orifice. This had been found to be prac- by thl t 6 teste to determine the lossesof head in orifices in:54:in.,-1-in., and pipe, conducted Sew ' ie^as Engineering Experiment Station, and also in the tests to determine the losses of head in ori- n,. 6-in., and 12-in. ntrw mn/liu>fAd hv tha -.# it- ri_a.---