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American Society of Heating and Ventilating Engineers Guide, 1929 the maximum capacities for different parts of the system as given in the tables. Tables 15 and 16 are for sizing pipe for vapor systems where the equivalent length of run exceeds 200 ft. Table 15 is for systems up to 400 ft. equivalent length and is based upon a total pressure drop of 2 oz. from the source of steam supply to the farthest heating unit. Table 16 is for larger systems where the equivalent length of run from the boiler or source of steam supply does not exceed 600 ft. It is based upon a totalpressure drop of 4 oz. Risers and branches to risers and heating units should not be loaded above their maximum capacity as given in Columns F and G. Table 17 is a pipe sizing table for small vacuum pump systems where the equivalent length of run from the boiler or source of steam supply to the farthest heating unit ranges from 100 to 600 ft. The table is based Table 10. Pipe Sizes for One-Pipe, Gravity, Low Pressure Steam Heating System, where Equivalent Length of Run from Boiler or Source of Supply to the Farthest Radiator does not exceed 200 ft. Capacity in Sq. Ft. of Equivalent Radiation Based on Total Pressure Drop of 1 oz. per 100 ft. Pipe Size Inches Supply Main Dripped and Branches to Risers Dripped Steam and Condensate flowing in the same direction. AB i IK ih 2 2H 3 3K 4 56 122 190 386 635 1163 1737 2457 Supply Risers Up-Feed C 25 45 98 152 288 464 799 1144 1520 Branches to Supply Risers and Radiators Not Dripped Wet Return Main D* B Dry Return Main P 20 55 81 165 260 475 745 1110 700 320 1200 1900 . 670 1058 4000 6700 2300 3800 10,700 -- 7000 10,000 -- -- Radiator Valve Sizes and Vertical Connections G 20 55 81 165 S 4546 -- 2180 -- -- 6 7462 ' -- ----- -- -- __ . . to-vj / American Society of Heating and Ventilating Engineers \ Not to be Reprinted With- Copyrigntt 1V^7 ^ Healing and Piping Contractors National Association f out Special Permission, Radiator branches more than 8 ft. in length should be one size larger than shown in Col. D. Note 1.--These tables apply where pipes are properly reamed. No allowances for defective material or^ workmanship have been made. (Also see Tables 8 and 9). NoieS.--Capacities based on actual diameter of standard pipe. lb. condensation per square foot per hour equivalent radiation and: , :; Note 8.--Extra length to be added to straight run of pipe, for various fittings and valves to determine ' equivalent length. (See Table 4). Note 4.--Where it is necessary to drip a steam main, branch to riser or riser, same should be dripped- separately into wet return. Note 6.--Pitch of mains should be,not less than in. in 10 ft.; on horizontal branches to radiators and . risers at least in. in 10 ft. 96 IIIChapter --Steam Heating Systems and Piping upon a total pressure drop in the entire equivalent length from steam supply to farthest heating unit of 4 oz. Up-feed risers, branches to risers and heating units should not be loaded beyond the maximum capacities given in Columns H and I. Table 18 is similar to Table 17 and is for larger systems where the equivalent length of run ranges up to 1200 ft. It is based on a total pressure drop of 8 oz. in the entire equivalent length. In. designing any kind of a heating system it is well to avoid excessive pressure drop in any part of the system. While, under proper design and good workmanship, higher drop may give good results, it is generally not considered good practice to exceed a drop of 1 oz. in 100 ft. equivalent length. Table 11. Pipe Sizes for Two-Pipe, Gravity, Low Pressure Steam, where Equivalent Length of Run from Boiler or Source of Supply to Farthest Radiator does not exceed 200 ft. Capacity in Sq. Ft. of Equivalent Radiation Based on Total Pressure Drop of 1 oz. per 100 ft. Pcpb Sizes Inches A. K 1 Supply Main Dripped and Branches to Risers Dripped Steam and *' Condensate Flowing in same Direction Supply Risers Up-Feed Branches to Supply Risers and Radiators Not Dripped Return Risers B C. D* B _ 30 122 56 56 26 320 Wet Return Main F 700 Dry Return Main' Radiator Supply Valve G 320 H 30 56 Radiator Return Valve I 122 190 IK IK 2 2K 122 190 386 635 122 190 386 635 58 95 195 395 670 1058 2300 3800 1200 1900 4000 6700 670 1058 2300 3800 122 190 386. 386 --- 3 3K 1163 1737 1129 1548 700 1150 7000 10,700 10,000 -- 7000 10,000 -- -- 4 - 2457 2042 1700 ---- -- ----- 5 4546 .--.. 3150 ---- -- -- 6 7462 -- -- -- -- -- ----- - Copyright 1927 ^ American Society op Heating and Ventilating Engineers \ Not to be Reprinted With* * l Heating and Piping Contractors National Association ) out Special Permission Radiator branches more than 8 ft. in length should be one size larger than shown in Col. D. Note I.--These tables apply where pipes are properly reamed. No allowances for defective material or workmanship have been made. (Also see Tables 8 and 9). . Note 8.--Capacities based on % lb. condensation per square foot per hour equivalent radiation and actual diameter of standard pipe. Note 8.--Extra length to be added to straight run of pipe for various fittings and valves to determine equivalent length. (See Table 4.) Note 4--Where it is necessary to drip a supply main, supply riser or branch to a supply riser, same should be dripped separately, into a wet return or through an adequate seal into a dry return. Never drip a supply pipe into a dry return except through an adequate seal. . Note 5.--Pitch of mains should not be less than in. in 10 ft.; on horizontal branches to radiators and risers at least >2 in. in 20 ft. 97