Document RjEN4nxY2OBYQYZ2YGXDdnyvV

510 CHAPTER 21 1956 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 or Heating and Air-Conditioning Engineers. . CAPACITIES OF STEAM MAINS AND RISERS i Special Capacities for One-Pips Systems Only Pipe Size In. Dibection op Condensate Flow in Pipb Line Radi- With the Steam in One-Pipe and Two-Pipe Syatama A psi or lOz Drop j*j psi or jo. Drop A psi or 1 Os Drop 1 psi or 2 Oz Drop Jp or. 4 Oz Drop Jpsi . or 8 0s Drop Against the Steam Two-Pipe Only Supply Risers Up- star RadiValves ator and and Vertical ` Riser Feed Con- Run- Vertical Hori zontal sec outs tions B C D B F a H* r KV Capacity Expressed in Square Feet EDS _30 30) ___ ' 25 ___ 1u n 2 2i 3 31 4 5 6 8 10 12 16 39 87 124 273 449 822 1 230 1740 46 100 155 315 518 948 1 420 2,010 56 122 190 386 635 1,160 1)740 2,460 79 173 269 546 898 1,650 2)460 3,480 111 245 380 771 1,270 2,330 3,470 4,910 157 346 538 1,091 1,800 3,290 4,910 6,950 56 122 190 386 635 1,130 1,550 2,040 34 75 108 195 395 700 1,150 1,700 45 98 152 288 464 800 1,140 1,520 3210 3*710 4,550 6,430 9,090 12,900 4,200 3,150 -- 5,280 6,100 7,460 11*000 12)700 15,500 10,550 21,970 14,900 31,070 21,100 7,200 5,600 43,900 15,000 12,000 . -- --- 20*000 23)100 28,300 40,100 56,700 80,200 28,000 23,000 -- 32,000 37,100 45,500 64,300 91,000 129,000 46,000 38,000 61,000 69,700 84,800 121,000 170,0)0 242,000 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 11 H 2 21 3 31 4 5 6 8 10 12 16 8 10 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 40 87 135 273 449 822 1,230 1,740 J.210 5,280 11,000 20,000 32,200 60,500 86 14 9 11 31 19 20 48 27 38 971 49 72 159 .99 116 282 175 200 387 288 286 511 -425 ; 380 788 -- 1,400 - -- 3,000 -- 5,700 -- 9,500 -- 19,000 -- 7 16 23 42 7 7 16 23 42 65 119 186 278 545 All Horizontal Maina and Down-Feed Risera UpFeed. Risers Mains and Un dripped Runouts UpFeed Risers Radi ator Con nec tions Run outs Not DripP$4 Note.--Steam at an average pressure ol 1 psig is usea ss a oasis lor caieuiauug _______________________ are in psi per 100 ft of equivalent run--baled on pipe properly reamed. * Do not use Column H for drops of 1/24 or 1/32 psi; substitute Column C or Column B os required. b Do not use Column J for drop 1/32 pei except on sixes 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 511 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 rim 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 ye 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 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 now in the same direction, use j^-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 W-psi drop is being used, the steam main and dripped runouts would be