Document 3QYDkmGpw8gNXrQD6eMRJqG7O

476 CHAPTER 20 1951 Guide Table 5. Steam Pipe Capacities for Low Pressure Systems (Reference to this table will be by column letter A through L) This table is based on pipe size data developed through the research investigations of the American Society op Heating and Ventilating Engineers. CAPACITIES OF STEAM MAINS AND RISERS Special Capacities for Pipe In. A With the Steam in One-Pipe and Two-Pipe Systems tVpsi $ Os Drop B A psi IDr0o1p C A pai 1 Oz Drop D I psi 2 Oz Drop E i psi 4 Oz Drop F i psi 8 Oz Drop O Against the Two-Pipe Only Vertica Hori zontal H* . Radi ator Supply Valves Risers and Up- Vertica Feed Con nec tions K Capacity Expressed in Square Feet E D R Radiand Run outs IA . i 1 H li 2 2i 3 3i 4 5 6 8 10 12 16 30 46 87 100 134 155 273 315 449 518 822 948 1,230 1,420 1,740 2,010 3,210 3,710 5,280 6,100 11,000 12.700 20,000 23.100 32.000 37.100 61.000 69.700 30 56 122 190 386 635 1,160 1,740 2.460 4,550 7.460 15.500 28,300 45.500 84,800 -- 79 173 269 546 898 1,650 2,460 3,480 6,430 10,550 21,970 40,100 64,300 121,000 in 157 245 346 - 380 538 771 1,091 1,270 1,800 2,330 3,290 3,470 4,910 4,910 6,950 9,090 12.900 14,900 21,100 31,070 43.900 56,700 80,200 91,000 129.000 170,000 242.000 36 56 122 190 386 635 1,130 1,550 2,040 4.200 7.200 15.000 28.000 46.000 88.000 31 75 108 195 395 700 1.150 1,700 3.150 5,600 12,000 23.000 38.000 76.000 26 4S 98 152 288 464 800 1,140 1,520 28 62 93 169 --. 28 62 .93 169 260 475 745 1,110 2,180 Capacity Expressed in Pounds per Hour i8 ;8 1 n u 2 21 3 31 4 5 6 8 10 12 16 10 12 14 22 25 31 34 39 48 68 79 97 112 130 159 206 237 291 307 355 434 - 435 503 614 806 928 1,140 1,320 1,520 1,870 2,750 3,170 3,880 5,010 5,790 7,090 8,040 9,290 11,400 15,100 17,400 21,200 20 43 67 137 225 411 614 869 1,610 2,640 5,490 10,000 16,100 30,300 28 61 95 193 318 581 869 1,230 2,270 3,730 7,770 14,200 22,700 42,400 40 14 9 87 31 19 135 48 27 273 , 97 49 449 159 99 822 282 175 1,230 387 288 1,740 511 425 3,210 1,050 788 5,280 l ;800 1,400 11,000 3,750 3,000 20,000 7,000 5,700 32,200 11,500 9,500 60,500 22,000 19,000 6 11 20 38 . 72 116 200 286 380 7 16 23 42 7 7 16 23 42 65 119 186 278 545 * All Horizontal Mains and Down-Feed Risers Mains UpFeed Risers. and Uniripped Run Up-. Feed Risers outs Radi ator Ruq* Cori- outs nec- . Not tions JDripped Not*---Steam at an average pressure of 1 psig ia used as a basis for calculating capacities. AU drops showi: are inpri per 100ft of equivalentrun--based on pipe properly reamed. Do not use Column B for drops of 1/24 or 1/32 psi; substitute Column Cor Column B as required, b Do not use Column J for drop 1/32 psi except on sixes 3 in. and over; below 3 in. substitute Column I 0 On radiator runouts over 8 ft tong increase one pipe size over that shown in Table 5. Steam Heating Systems 477 critical velocities of the steam to permit the counter flow of condensate without noise. Return piping may be sized with the aid of Tables 6 and 7 where pipe capacities for wet, dry, and vacuum return lines are shown for the pres sure drops per 100 ft corresponding to the drops in Table 5. It is cus tomary to use the same pressure drop on both the steam and return sides of a system. Example 2. What pressure drop should be used for the steam piping of a system if the measured length of the longest run is 500 ft, and the initial pressure is not to be over 2-psig? . Solution. It will be assumed, if the measured length of the longest run is 500 ft., that when the allowance for fittings is added the equivalent length of run will not exceed 1,000 ft. Then, with the pressure drop not over one-half of the initial pressure, the drop could be 1 psi or less. With a pressure drop of 1 psi and a length of run of 1,000 ft, the drop per 100 ft would be A psi, while if the total drop were J psi, the drop per 100 ft would be Je psi. .In the first instance the pipe could be sired according to Column D for A psi per 100 ft, and in the second case, the pipe could be sized accord ing to Column C for psi. On completion of the sizing, the drop could be checked by taking the longest line and actually calculating the equivalent length of run from the pipe sizes determined. If the calculated drop is less than that assumed, the pipe size is all right; if it is more, it is probable that there are an unusual number of fittings involved, and either the lines must be straightened or the column for the next lower drop must be used, and the lines resized. Ordinarily, resizing will be unnecessary. TABLES FOR PIPE SIZING FOR HIGH PRESSURE 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. Temperatures are controlled by a modulating or throttling type thermostatic valve con trolled by the air temperature in the room; fan inlet or outlet. Tables 8 to 11 may be used for the sizing of steam and return piping for systems of 30 and 150 psi pressure at various pressure drops. These tables are based on Babcock's formula, and have been used as the basis of design for a number of years. SIZING PIPING FOR ONE-PIPE GRAVITY SYSTEMS Gravity one-pipe air-vent systems, in which the equivalent length of run does not exceed 200 ft, should be sized by means of Tables 5, 6 and 7 as follows: 1. For the steam main and dripped runouts to risers where the steam and condensate flow in the same direction, use A-psi drop (Column D). 2. Where the riser runouts are not dripped and the steam and condensate flow in opposite directions, and also in the radiator runouts where the same condition occurs, use Column h. 3. For up-feed steam risers carrying condensate back from the radiators, use Column J. 4. For down-feed systems, the main risers of which do not carry any radiator con densate, use Column H. 5. For the radiator valve size and the stub connection, use Column K. 6. For the dry.return main, use Column U. 7. For the wet-return main use Column T. On systems exceeding an equivalent length of 200 ft, it is suggested that the total drop be not over J psi. The return piping sizes should corre spond with the drop used on the steam side of the system. 'Thus, where ^-psi drop is being used, the steam main and dripped runouts would be