Document 4J93OL4oYQZMjp92k7R5jBy6G

498 CHAPTER 21 1954 Guide Table 5. Steam Pipe Capacities fob 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 of Heating and Ventilating Engineers. CAPACITIES OF STEAM MAINS AND RISERS I Special Capacities fob IOnb-Pipb Systems Only Pipe Sub In. Dibbction o Condensate Flow in Pipe Line Radi- ator Radi With the Steam in One-Pipe and Two-Pipe Syatema A P=i or 1 o Drop A pa or i Os Drop *OPr 1 Os Drop i pa or 20s Drop 40s Drop i pal or 8 0* Drop Against the Steam [Supply Risers Valves I and I ator and Two-Pipe Only UpFeed Vertical Con Riser Run Vertical Hori zontal nec outs tions B CD B Capacity Expressed in Square Feet E D R 30 1 11 Hv 2 21 3 31 4 5 6 8 10 12 16 39 46 56 87 . 100 122 134 155 190 273 315 386 449 518 635 822 948 1,160 1,230 1,420 1,740 I,740 2,010 2.460 3,210 3,710 4,550 5,280 6,100 7.460 II,000 12.700 15.500 20,000 23,100 [28,300 32,000[37,100 45.500 |61,000 69.700[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 llll 245 3801 771 1,270| 2,330 3,470 4,910 9,0901 14,900 31,070 56,700 91,000] 170,000 30 _ I 25 157 56 34 45 122 75 98 190 108 152 386 195 288 635 395 464 1,130 700 800 1,550 1,150 1,140 ) 2,040 4,200 1,700 3,150 1,520 '-- 3 7,20C 5,600 -- 315,000 12,000 -- 0 28,00( 23,000 0 46,00( 38,000 -- 0 88,000 76,000 -- __ 28 62 93 169 -- -- -- . -- -- ' . -- -- --- -- -- 28 62 93 169 260 475 745 1,110 2,180 -- -- Capacity Expressed in Pounds per Hour _8 6_ 1 1 11 n 2 21 3 31 4 5 6 8 10 12 16 8 10 12 14 22 25 31 34 39 48 68 79 97 112 130 159 206 237 291 307 355 4341 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 17,400 121,200 20 43 67 137 225 411 614 869 1,610 2,640 5,490 10.000 16.1001 30,300| 28 61 95 193 318 581 86E 1.23C 2,27( 1 40 87 135 273 449 822 1,230 1,740 3,210 3.7301 5,280 7.770, 11,000 14,200 20,000 22,700] 32,200 42,400| 60,500 14 9 31 19 48 27 97 49 159 99 282| 175 387 288 511 425 1,050 788 1,800 1,400 3,750| 3,000 7,000 5,700 9,500 >19,000 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 RiBOT Mains and Up- UnFeed drippec Risers Run- outs UpFeed Risers ator Con* neotiona Run outs Not Dripped I Note.--Steazn at an average pressure of 1 prig is used as a basis for calculating capacities. AH drops shown are *inDpoeni poet rus1e00CfotloufmenquHivfaolrednrtorpusno--f b1a/2s4edoor n1/3p2ipepepi;rosupbesrltyitureteamCeodlu. mn 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 Pitch 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 499 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 oj 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 rim 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 ^ psi, while if the total drop were 1 psi, the drop per 100 ft would be /o psi. In the first instance the pipe could be sized according to Column D for ^ 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- Pot the steam main and dripped runouts to risers where the steam and condensa?*flow in the same direction, use ,V*psi drop (Column D). 2. Where the riser runouts are not dripped and the steam and condensate flow i> opposite directions, and also in the radiator runouts where the same condition occuir 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 i psi. The return piping sizes should corre spond with the drop used on the steam side of the system. Thus, where ri-psi drop is being used, the steam main and dripped runouts would be