Document yrY63vL39MrennJnJy55yYQg2

. *54 CHAPTER 24 1946 Guide - (or each radiator or heating unit, to permit its removal without requiring the draining of the entire system. .One valve may be of the lo.ck shield type so that it may be used for balancing flow. All large systems should be provided with extra stop and drain valves, suitably located so that parts of the system may be isolated for repairs without making it necessary to drain the water from the entire system. FLOW OF WATER IN GALLONS PER MINUTE To find friction when temperature drop is other than 20 deg, multiply the actual heat conveyed by /_ 20 ' \aactual temp drop, and read the corresponding friction. GRAVITY CIRCULATION PIPE SIZES In gravity hot water heating systems the difference in density between the flow and return water produces the required natural circulation of . the water. The design temperature difference is usually assumed from between 20 to 35 deg. After having determined the temperature dif/ ference and the temperature, of the flow' water, data given in Fig. 5 can ' be' used to obtain the head available for circulation. With this infor. mation determined, pipe sizes which will have-a resistance equal to the Hot Water Heating Systems and Piping 455 Table 4. Friction (in Milinches) of Central Circular Diaphragm Orifices in Unions (One milinch equals 0.001 in.) DlAJdETER Of Orifices (INCHES) -------- ---;--------23 Velocity of Water in Pipe i** Inches per Second 4 |~ 6 | 8 | 10 j 12 f 18 %-in. Pipe 24 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 32,000 10,400 16,000 5200 8000 2600 . 4000 1300 2000 620 970 300 480 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 1-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 32,000 12,000 17,000 6400 9300 3700 5400 2200 3000 1300 1800 720 1100 37,000 2i,000 12,000 7000 4200 2400 65,000 37,000 22,000 .13,000 7400 4300 50,000 28,000 17,000 10,000 j li/fin. 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 60,000 18,000 40,000 12,000 26,000 0.55 0.60 0.65 0.70 0.75 0.80 0.85 850 600 400' 260 180 1900 1300 850 600 400 300 200 3300 '2300 1500 1100 760 540 380 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 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 2-in. Pipe 0.70 0.80 0.90 1.00 1.10 1.20 1.30 . 890 470 255 160 1850 975 560 340 214 3500 1800 1000 610 375 195 1 7400 3900 2200 1320 850 460 275 14,000 22,300 7400 .11,700 4200 6500 2520 4000 1600 2500 950 1360 525 980 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 Note.--The losses of head for the orifices in the lH-m. 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 head is.a function of the ratio of'the Hiamt#r of the pipe to that of the orifice.,- This had-been found to.be/ practically true in the tests to determine the tosses of head in orifices in &-in.,, 1-in-, and l}-ln. pipe, con-, 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).