Document NNaOwoKvp6Kpw5M169yw2RB0g

486 CHAPTER 20 1952 Guidi i ^ Table 5. Steam Pipe Capacities fob Low Phessube 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. -- Pipe Sub In. A CAPACITIES OF STEAM MAINS AND RISERS Special Capacities fob Onb-Pipb Systems Only Direction or Uondbnsate flow in fzpb ljnb With the Steam in One-Pipe and Two-Pipe Systems A pai - or -i it pai A pai ip 1 Os .Drop i psi aos Drop 1 psi 4 0* Drop J psi 8 0s Drop Against the ator Supply Valves Two-Pipe Only Risers and Vf- Vertical Feed Con Vertical Hori zontal nec tions Radi ator and Riser Run outs B C D B F G H* /c Jb K L* Capacity Expressed in Square Feet E D R i 30 30 25 1 39 46 56 79 in 157 56 34 45 28 H 87 100 122 173 245 346 122 75 98 62 11 134 155 190 269 380 538 190 108 152 93 2 273 315 386 546 771 1,091 386 195 288 169 2 449 518 635 898 1,270 1,800 635 395 464 3 822 948 1,160 1,650 2,330 3,290 1,130 700 800 31 1,230 1,420 1,740 2,460 3,470 4,910 1,550 1.150 1,140 4 1,740 2,010 2.460 3,480 4,910 6,950 2,040 1,700 1,520 5 3,210 3,710 4,550 6,430 9,090 12.900 4.200 3.150 6 5,280 6,100 7.460 10,550 14,900 21,100 7.200 5,600 8 11,000 12.700 15.500 21,970 31,070 43.900 15.000 12,000 10 20,000 23.100 28,300 40,100 56,700 80,200 28.000 23.000 12 32.000 37.100 45.500 64,300 91,000 129.000 46.000 38.000 16 61.000 69.700 84,800 121,000 170,000 242.000 88.000 76.000 28 62 93 169 260 475 745 1,110 2,180 Capacity Expressed in Pounds per Hour i8 '8 1 10 12 14 20 28 40 14 9 n 22 25 31 43 61 87 31 19 H 34 39 48 67 95 135 48 27 2 68 79 97 137 193 273 97 49 21 112 130 159 225 318 449 159 99 3 206 237 291 411 581 822 282 175 31 307 355 434 614 869 1,230 387 288 4 435 503 614 869 1,230 1,740 511 425 5 806 928 1,140 1,610 2,270 3,210 1,050 788 6 1,320 1,520 1,870 2,640 3,730 5,280 1,800 1,400 8 2,750 3,170 3,880 5,490 7,770 11,000 3,750 3.000 10 5,010 5;790 7;090 .10,000 14,200 20,000 7,000 5,700 12 8,040 9,290 11,400 16,100 22,700 32,200 ,11,500 9,500 16 15,100 17,400 21,200 30,300 42,400 60,500 22,000 19.000 6 11 7 20 16 38 23 72 42 116 200 286 380 7 7 16 23 42 65 119 186 278 545 All Horizontal Mains and Down-Feed Risers Mains UpFeed Risers and Un dripped Run outs UpFeed Risers Radi ator Con nec tions Run outs Not Dripped Note.--Steam at an average pressure of 1 psig is used as a basis for calculating capacities. All drops shown are in psi per 100 ft of equivalent run--based on pipe properly reamed. * Do not use Column B for drops of 1/24 or 1/32 psi; substitute Column C or Column B as required. ' b Do not use Column J for drop 1/32 psi except on sizes 3 in. and over; below 3 in. substitute Column B. c Fitch of horizontal runouts to risers and radiators should be not less than 1/2 in. per ft. Where this pitch cannot be obtained, runouts over 8 ft in length should be one pipe size larger than called for in Table 5. Steam Heating Systems 487 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 I 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 4 psi, the drop per 100 ft would be A psi. In the first instance the pipe could be sized 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 A 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 Dumber 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 II 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 L. 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 A-psi drop is being used, the steam main and dripped runouts would be