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American-Society of Heating and Ventilating Engineers Guide, 1932 c Table 10. Pipe Sizes, for One-Pipe; Air-Vent, Low Pressure Steam Heating Systems, where Equivalent Length of Run from Boiler or Source of Supply . to Farthest Radiator Exceeds 200 Ft. Capacity in Sg. Ft. of Equivalent Radiation Based on 4 oz. Total Pressure Drop ^ Pipe. Size Inches A i IX ix 2 2X 3 3X 4 5 6 8 10 12 orEquivalent Length Pipe prom Boiler to Farthest Radiator, Including Main and Riser. (See Note 6.) ' Supply Main Dripped and Branches to Risers Dripped-- Steam and Condensate flowing in same direction. 100 Ft B in 245 200 Ft. C 79 173 300 Ft D 65 141 400 Ft E 56 122 500 Ft ? 49 110 600 Ft a 46 100 380 269 220 190 165 155 771. 546 446 386 345 315 1270 2326 898 1645 734 1342 635 1163 568 1040 518 948 3474 4914 2457 3475 2006 2828 1737 2457 1552 2196 1419 2011 9092 14,924 6429 10,553 5250 8618 4546 7462 4062 6669 3712 6094 31,066 56,689 21,967 40,085 17,935 32,730 15,533 28,345 13,880 25,334 12,682 23,144 90,985 64,336 52,530 45,492 40,660 37,145 Maximum Capacities Supply Risers Up-Feed Branches to Supply Risers ana Radiators Not Dripped . Radiator Valves and Vertical Connections B . . /o : / 45 20 . 20 98 55 .55 152 81 288 165 81 165 464 260: 799 '. 475 1144 1520 745 1110 -- 2180 ---- ; . -- -- -- -- -- -- -- Pipe Inches K Dbt Return Main Equivalent Length or Run' prom Boiler to Foot or Farthest Riser in Feet 200 500 LMN0 P Q Wet Return Main. Equivalent Length or Run from Boiler to Foot or Farthest Riser.in Feet 300 400 R TDVw 1 460 412 368 320 275 227 1400 1000 820 700 640 . 580 in 962 868 770 670 579 480 2400 1700 1390 1200 1080 990 , 1512 1362 1210 1058 909 757 3800 2700 2180 1900 1710 1570 2 3300 2960 2640 2300 1980 1630 8000 5600 4520 4000 3560 3240 2X 5450 4900 4380 3800 3300 2770 13,400 9400 7600 6700 6000 5300 3 10,000 9000 8000 7000 6000 5000 21,400 15,000 12,500 10,700 9400 8500 3X 14,300 12,900 11,500 10,000 8600 7200 32.000 22,000 18.500 16,000 14,400 13,200 4 21,500 19,300 17,200 15,000 12,900 10,700 44.000 31,000 25.500 22,000 19,900 18,300 rvmvrioht- iq-v7 / American Societt or Heatinq and Ventilating Engineem \ Not to be Reprinted With- pyrig , | Heating and Piping Contractor! National Angcialidn - / out Special Permission INSTRUCTIONS FOR USING TABLE 10 al. Radiator branches more than 8 ft. in length should be one size larger than shown in Column I. 2. These tables apply where pipes are properly reamed. No allowances for defective material or workmanship have been made. (Also see Tables 7 and 8). 3. Capacities based on X lb. condensation per square foot per hour equivalent radia tion and actual diameter of standard pipe. 4. Extra length to be added to straight run of pipe for various fittings and valves to determine equivalent length. (See Table 4). 146 ' ` i 1 i ; * 1 } j . : ;! ' J f : t e j w j | Chapter 9--Steam Heating Systems and Pipe Sizes It may be desirable in some cases to utilize a condensation pump rather than a vacuum pump where the heaters are too close to, or must be below, the boiler water line. Fig. 6 illustrates an approved hook-up for such a condition though, of course, the apparatus may be used with a wet return as well as with the dry return shown. It will be noted that each heater has a trap. When a condensation pump is used with a one-pipe system a false water line should be established sq that the sealing of each dry return against the others, so important with one-pipe systems, shall.be main tained. -Sometimes, in this contingency, it is desirable to place a float trap on the end of each separate dry return connection to the pipe which supplies the pump-suction. Piping systems used with vacuum pumps where zone control of the heating is employed, demand the subdivision of the supply piping with valves for each division. The return piping for each of these divisions also should be separate and in many cases a separate vacuum pump is provided for each zoned division. There are a number of meritorious proprietary types of steam, vacuum return line, differential, and vapor.heating systems, which vary in certain particulars from the foregoing typical examples. These systems have INSTRUCTIONS FOR U&ING TABLE 10 (Continued) 5. Mains are to be proportioned according to the equivalent length of run from the boiler or source of supply to the farthest radiators supplied by the main. Determine equivalent length of run then use figures in corresponding Columns (B to G) for supply mains; (L to Q) for dry-return mains; (R to W) for wet-return mains for sizing the entire run. For example: If the distance from boiler or source of supply to the farthest radiator on the longest main should be 300 ft., all mains are to be sized from Column D; if 400 ft., Column E; if 600 ft., Column G. Risers are to be proportioned according to the equivalent length of run from the boiler or source of supply to the farthest radiator on each particular riser. Determine the distance to the farthest radiator then use the figures in the corre sponding Columns (B to G) for sizing each riser; providing the amount of radiation for that riser does not exceed amounts shown in Column H. Where riser capacities are found to be in excess of amounts in Column H, step up to necessary size indicated in that column. For example: If the distance from the boiler or source of supply to the farthest radiator on a supply riser is 300 ft., that riser is to be sized from Column D, providing' the amount of radiation does not exceed the amount shown in Column H. If the amount exceeds that in Column H, use amounts shown in Column H for sizing that entire riser. If another riser taken from the same main as the one above is only 200 ft., this riser should be sized from Column C, providing the amount of radiation does not exceed that as shown in Column H. 6. For practical purposes the pipe sizes on the usual heating system may be determined by using the pressure drop indicated by the longest main and riser on that system, neglecting the separate computations for each separate shorter run. 7. Where it is necessary to drip a steam main, branch to riser or risers, same should be dripped separately into wet return. 8. Pitch of mains should be not less than X in. in 10 ft.; on horizontal branches to radiators and risers'at least X in. in 10 ft. -- 9- In general it is desirable not to have a supply main smaller than 2 in. in diameter, When the supply main is larger than 2X in. at the beginning, it is desirable that it shall not be smaller than 2l/ in. at the end. 147