Document MM6y4YvK5Q8KqKKpEOqpGMYxL

American Society of Heating and Ventilating Engineers Guide, 1932 Table 12. Pipe Sizes for Two-Pipe Vapor11 Systems, where Equivalent Length OF RUN FROM BOILER OR SOURCE OF SUPPLY TO FARTHEST. Radiator does not exceed 200 Ft. Capacity irt Sq. Ft. of Equivalent Radiation Based on Total Pressure Drop of 1 oz. per 100 ft. Pipe Sob Inches Supply Main Dripped and Branches to Risers , Dripped Steam and Con densate flowing in same direction.. AB . 3A l 56 Supply Risers Dp-Feed Branches to Supply Rnnggw AND RADIATORS Nor Dripped Return Risers C 30 56. B 190 26 450 Wet Return Main Dry Return Main ? _ 700 -V .-C 320 lA 122 lA : 190 2 386 2A 635 3 1163 1737 122 190 386 635 1129 1548 . . 58 95 195 395 700 1150 990 1500 3000 -- -- 1200 1900 4000 6700 10,700 ----------------- 670 . : 1058 ; . 2300 3800 7000 10,000 4 2457 2042 1700 -- -- -- 5 4546 -- 3150 -- -- -- 6 7462 Different makes of supply and return valves, steam traps and other specialties vary as to capacity, therefore use size as recommended for any particular make. Vertical connections to.be of same size as valve and trap used. Return horizontal runout to be not less than $ In. .... r. .... , Q>_ f American Society o? Heating and Ventilating Engi^krs I Not to be Reprinted Wlth- tAJpyngnt, ^ Heating and Piping Contractor* National Association / out Special Permission INSTRUCTIONS FOR USING TABLE 12 al. Radiator branches more than 8 ft. in length should be one size larger than,shown in Column D. b2. This table is for systems which are open to atmosphere or operate under slight pressure or partial vacuum without use of vacuum pumps. 3. These tables apply where pipes are properly reamed. No allowances for defective material or workmanship have been made. (Also see Tables 7 and 8). .4. Capacities based on A lb. condensation per square foot per hour equivalent radiation and actual diameter of standard pipe. 5. Extra length to be added to straight run of pipe for various fittings and valves to determine equivalent length. (See Table 4). 6. 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. The drip for a vapor or vacuum system may be taken into a dry return through a steam trap. 7: Pitch of mains should be not less than A in. in TO ft.; on horizontal branches to radiators and risers at least A in. in 10 ft. 8. In general it is desirable not to have a supply main smaller than 2 in. in diameter. When the supply main is larger than 2A in. at the beginning, it is desirable that it shall not be smaller than 2J6 in. at the end. 150 Chapter 9--Steam Heating. Systems and Pipe Sizes.... pr spaces where overheating is likely to occur, or:where the same tempera tures are not desired in all. the rooms or spaces of the building. Orifice Control1 In using the last method, the fate of flow of steam into a radiator can be controlled by means of (1) a restriction of variable area such as is obtained by throttling the radiator valve, or (2) a fixed restriction, such as a fixed orifice, a variable flow being obtained by varying the pressures on the two sides of the orifice. '"i The use of a fixed orifice makes it possible to reduce the heat output of a radiator to any desired extent. The radiator may be kept full of steam when the maximum heat output is needed, by adjusting the pressure on the inlet side of the orifice so that it is sufficiently above that in the radiator. In mild weather the flow of steam into the radiator may be reduced to such an extent by reducing the difference in pressure between the two sides of the orifice that only a small part of the radiator is heated. rTHEStaJEECTlONS SHOULD BE AS SHOUT AS HUCTICAL USNG ASFEW-, \lUBM5 AS POSSIBLE. IKE SIZES SHOULD PBEFEBIHV BE NOT SMALLEB THAN GIVEN IN TABLE BELOW. (KATE ABEA PIPE SIZE. A Sa FEET OB LESS-------------- W Fig. 7. THESE PIPES MAT K ANY SIZE CONSIDEBED PB0PEB FOB FEEDING1 BOILEBS AND LESS THAN STEAM CONNECTIONS H TABLE ABOVE. Using the Hartford Return Connection Between these extremes, the pressure differential may be adjusted to'give the flow of steam required for weather conditions encountered at any time during the heating season. Radiator orifices can be inexpensively made and installed.' When an orifice system is properly operated, it is possible to obtain highly satis factory control of building temperature, resulting in economy in the use of steam for heating. For additional information on temperature control, refer to-Chapter 23. PIPING CONNECTIONS Hartford Return Connections The Hartford return connection illustrated in Fig. 7 and in other piping layouts in this chapter is recognized as safer and preferable to q iFoLa1d!SOI,al intonation on this subject, refer to Flow of Steam through Orifices into Radiators, by o. a. bantord and C. B. Sprenger [Heating, Piping and Air Conditioning, June. 1931]. 151