Document pevZZNV42mz6Vz8MBE2bd626a

522 CHAPTER 20 1957 Guide Table 5. Steam Pipe Capacities fob Low Pbesscbe 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 Americau Society or Heating and Ara-Conditioning Engineers. CAPACITIES OF STEAM MAINS AND RISERS i Special Capacities roil [Ohb-Pipr Systems Only Sub In, A Dntacnolf or Condensate Flow in Pipe Like With the Steam in One-Pipe end Two-Pipe Systems A psi or 4 0* Drop or 1 Oz Drop or 1 Os Drop 4 psi or 20s Drop \ pa or 4 Os Drop 4 psi or 8 0s Drop Against the Steam Two-Pipe Only Vertical Hori zontal Supply UpFeed Radi ator Valves and Vertical Con nec tions Radi ator Riser outs B CD B F a B* r K L* Capacity Expressed in Square Feet E D R 1 __ 30 1 39 46 56 li 87 100 122 11 134 155 190 2 273 315 386 2J 449 518 635 3 822 948 1,160 3* 1,230 1,420 1,740 4 1,740 2,010 2,460 5 3,210 3,710 4,550 6 5,28C 6.100 7,460 8 11,000 12,700 15,500 10 20,00C 23,100 28,300 12 32.00C 37,10C 45,500 16 61,000 69,700 84,800 ___ 30 ___ 25 111 157 56 34 45 245 346 122 75 98 380 538 190 108 152 771 1,091 386 195 288 1,270 1,800 635 395 464 2)330 3,290 1,130 700 800 3,470 4,910 1,550 1,150 1.140 4,910 6,950 2,040 1,700 1,520 9,090 12,900 4,200 3,150 -- 14,900 21,100 7,200 5,600 -- 31,070 43,900 15,000 12,000 -- 56,700 80,200 28,000 23.000 -- 91,000 129,000 46,000 38,000 -- 1170,000 242,000 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 _ _i 1 H H 2 21 3 31 4 5 6 8 10 12 16 8 12 14 25 31 39 48 79 97 130 159 237 291 355 434 503 614 928 1,140 1,520 1,870 3,170 3,880 5,790 7,090 9,290 11,400 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 8 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 I,050 788 5,280 1,800 1,400 11,000 3,750 3,000 20,000 7,000 5,700 32,200 II,500 9,500 60,500 22,000 19,000 6 11 7 20 16 38 23 72 42 116 200 286 380 7 7 16 23 42 65 119 186 278 546 All Horizontal Mains and Down-Feed Risen UpFeed Risen and Un dripped Run UpFeed Risen outs Radi ator Con- Run outs Not DripP** Note.--Steam at an average pressure of 1 psig is used as a basis for calculating capacities. All drops sho^ are inDposni poet rus1e00CfotloufmenquHivfaolrednrtorpusno--f b1a/2s4edoor n1/3p2ippespi;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 e Pitch of horizontal runouts to risers and radiators should be not less than 1/2 in. per ft. Where this p1 cannot be obtained, runouts over 8 ft in length should be one pipe size larger than called for in Table o. Steam Heating Systems 523 length of run is not usually known at the outset; hence, it may be necessary to assume some pipe size at the start. Such an assumption frequently is considerably in error, and a more common and practical method is to assume the length of run and to check this assumption after the pipes are sized. For this purpose the length of run usually is taken as double the actual length of pipe. TABLES FOR PIPE SIZING FOR LOW PRESSURE SYSTEMS* Tables 5, 6, and 7 are based on the actual inside diameters of the pipe and the condensation of \ lb (4 oz) of steam per square foot of equivalent direct radiation (abbreviated EDR) per hour. The drops indicated are drops in pressure per 100 ft of equivalent length of run. The pipe is assumed to be well reamed and without unusual or noticeable defects. Table 5 may be used for sizing piping for steam heating systems by pre-determining the allowable or desired pressure drop per 100 equivalent feet of run, and reading from the column for that particular pressure drop. This applies to all steam mains on both one-pipe and two-pipe systems, vapor systems, and vacuum systems. Columns B to G, inclusive, are used where the steam and condensate flow in the same direction, while Columns H and I are for cases where the steam and condensate flow in opposite directions, as in risers and runouts that are not dripped. Columns J, K, and L are for one-pipe systems and cover riser, radiator valve and vertical connection sizes, and radiator and runout sizes, all of which are based on the 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 i: 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 Ho psi, while if the total drop were H psi, the drop per 100 ft would be Ho psi. In the first instance the pipe could be sized according to Lolumn D for Ho psi per 100 ft, and in the second case, the pipe could be sized accord ing to Column C for Ha 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 We 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