Document kDx0bj80KVXMZ13kxwB6yQvZD

432 CHAPTER 23 1946 Guide Table-9. Steam Pipe Capacities for 30 psi Steam Systems Capacity Expressed in Pounds per Hour (Steam and Condensate Flowing in Same Direction) Pipe Size Inches M l 1M-. ik .2 m 3 ' 3K 4 5 6 8 10 . .12 -- Drop in Pressure--Pounds per 100 Ft in Length H 15 31 69 107 217 358 651 979 . 1,386 2,560 4,210 8,750 16,250 25,640 H 22 46 100 154 313 516 940 1,414 2,000 3,642 6,030 12,640 23,450 36,930 14 31 63 141 219 444 730 1,330 2,000 2,830 5,225 8,590 17,860 33,200 52,320 % 38 77 172 267 543 924 1,628 2,447 3,464 6,402 10,420 21,865 40,625 64,050 1 45 89 199 309 627 1,033 1,880 2,825 4,000 7,390 12,140 25,250 46,900 74,000 2 63 125 281 437 886 1,460 2,660 4,000 5,660 10,460 17,180 35,100 66,350 104,500 mined pressure by varying the vacuum in the return lines, or by varying the pressure in the supply lines and the vacuum in the returns: The valves are frequently manually set from a remote location, guided by tem perature indicating stations in the building; or thermostatically controlled from a thermostat on the roof, which automatically measures the dif ferential of outside and inside temperatures. Since the range .through which the pressures may be varied is usually from 0 to 4 psi gage, the control should be capable of maintaining close regulation to maintain the desired space temperatures, particularly in mild weather. A recommended orifice schedule is shown in Table 8. Some systems use orifices not only in radiator inlets but also at different points in the steam supply piping for the purpose of balancing the system to a greater extent. In this manner the difference between the initial and terminal Table 10. Steam Pipe Capacities foe 150 psi Steam Systems Capacity Expressed in Pounds per Hour (Steam and Condensate Flowing in Same Direction) Inches . %. i . ik ik 2 2K . 3 3H 4 5 '. '6 8 10 12 M 29 58 . 130 203 412 683 1,237 1,855 2,625 4,858 7,960 16,590 . 30,820 48,600 Drop in Pressure--Psi per 100 Ft in Length x 41 82 185 287 583 959 1,750 2,626 3,718 6,875 11,275 23,475 43,430' 68,750 K 58 117 262 407 . 825 1,359 2,476 3,715 5,260 9,725 15,950' 33,200 61,700 97,250 .% 71 143 320 497 1,010 1,650 3,020 4,550 6,430 11,900 19,500 40,000 75,600 119,000 82 165 370 575 1,167 1,920 3,500 5,250 7,430 13,750 22,550 46,950 87,250 137,600 2. 116 233 523 813 1,650 2,710 4,940 7,420 10,500 19,450 31,850 06,400 123,400 194,400 5 184 369 827 1,290 2,600 4,290 7,820 11,740 16,620 30,750 50,400 105,000 195,000 307,400 Steam. Heating Systems and Piping '_____________________________ ____________ 433 Table 11. Return Pipe Capacities for 30 psi Steam Systems Capacity Expressed in Pounds per Hour Pipe Size INCHES K 1 IK IK 2 2K 3 3H 4 5 6 H 115 230 485 790 1,575 2,650 4,850 7,200 10,200 19,000 31,000 Drop in Pressure--Pounds per 100 Ft in Length H 170 . 340 ' 710 1,155 2,355 3,900 7,100 10,550 15,000 27,750 45,500 M 245 490 . 1,025 1,670 3,400 5,600 10,250 15,250 21,600 40,250 65,500 . .H 308 615 1,285 2,100 4,300 7,100 12,850 19,150 27,000 55,500 83,000 1 365 730 1,530 2,500 5,050 8,400 15,300 22,750. 32,250 60,000 98,000 pressure in the steam main may be compensated to a great extent. For example, if the initial pressure was 3 psi gage and the pressure at the end of the main was 2 psi, an orifice could be used in each branch for the purpose of obtaining a more uniform pressure throughout the system. Such a provision may be particularly useful in this system for branches close to the boiler where the- drop in the main has- not yet been produced. Some orifice systems are'proprietary. HIGH PRESSURE STEAM SYSTEMS Many of the recent installations of heating systems for large industrial type buildings have been designed for the use of high pressure steam, that is, without the use of pressure reducing valves. Such systems usually involve the use of unit heaters or large built-up fan units with blast heating coils. Pressures on these systems vary from 30 to 150 psi. Tem peratures are controlled by a modulating or throttling type thermostatic valve controlled by the air temperature in the fan outlet. Tables 9 to 12 may be used for the sizing of steam and return piping for systems of 30 -and 150 psi pressure at various pressure drops. These Table 12. Return Pipe Capacities for 150 psi Steam Systems Capacity Expressed in Pounds per Hour Pipe Size Inches k 'i IK IK 2 2K 3 3K 4 5 .6 . H 156 313 650 1,070 2,160 3,600 6,500 9,600 13,700 25,600 42,000 Drop in Pressure--Psi per 100 Ft in Length H 232 462 960 1,580 3,300 5,350 9,600 14,400 20,500 38,100 62,500 a 360 690 1,500 2,460 . 4,950 8,200 15,000 22,300 31,600 58,500 - 96,000 K 465 910 1,950 3,160 6,400 10,700 ' 19,500 28,700 40,500 76,000 125,000 1 560 1,120' 2,330 3,800 7,700 12,800 23,300 34,500 49,200 91,500 150,000 2 890 1,780 3,700 6,100 12,300 20,400 37,200 55,000 78.500 146,000 238,000 -