Document zZ1BDZ1j1n6YOKBqwbvNZB7g

American' Society of Heating and Ventilating Engineers Guide, 1930 Table 12 is for comparatively small vapor systems.^ One ounce pressure drop may be understood to mean that the water in the vertical pipe which drains the end of the supply main will stand about 2 in. higher than the water line in the boiler, under normal conditions. 346 Chapter 20--Piping for Steam Heating Systems Table 13 shows the pipe sizes for larger vapor systems than those in Table 12. Using these sizes, the water in the vertical pipe which drains the end of the supply main, will stand about 4 in. higher than the water line in the boiler under normal operation. Table 14 shows the pipe sizes for vapor systems where a still greater difference in water line may be allowed between that in the boiler and in the return drop-pipe under normal operation. Where the basement Table 9. 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 I or. per 100 ft. PlFB Size Inches Supply Main Dbippxd and Branches to Rimma Dripped Steam and Condensate flowing in the same direction. AB % 1 56 m 122 m 190 2 386 ik 635 3 1163 3K 1737 4 2457 5 4546 6 7462 SOPPLT Risers Up-Feed C 25 45 98 152 288 464 799 1144 1520 .---- ------- - Branches to Supply Risers and Radiators Not Dripped Wet Return Main Dl E 26 55 81 165 260 475 745 1110 2180 -- 700 1200 1900 4000 6700 10,700 -- -- -- Drt Return . Main Radiator Valve Sizes and Vertical Connections FG 320 670 1058 2300 3800 7000 10,000 -- -- -- '26 55 81 165 ----- ,, ta~, j American Socleti 07 Heating and Ventiiatinq Enginekhs \ Not to be Reprinted Withwpyngni, nr/ ^ Heating and Piping Contradort National Attociaiion J out Special Permission INSTRUCTIONS FOR USING TABLE 9 1. Radiator branches more than 8 It. in length should be one size larger than shown in Col.-D- 2. These tables apply where pipes are properly reamed. No allowances for defective material or workmanship have been made. (See Tables 7 and 8). 3. Capacities based on *4 lb. condensation per square foot per hour equivalent radiation 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). 5. Where it is necessary to drip a steam main, branch to riser or risers, same should be dripped separately into wet return. 6. Pitch of mains should be not less than ]4 in. in 10 ft.; on horizontal branches to radiators and risers at least in. in 10 ft. -.-- 7. In general it is desirable not to have a supply main smaller than 2 in. in diameter. When the supply main is larger than 2K in. at the beginning, it is desirable that it idiall not be smaller than 2K in. at the end. 347