Document NnMjvKRKzDjjBo8aLoyo0dLg

Heating Ventilating Air Conditioning Guide 1938 Table 1. Maximum Allowable Capacities of Up-Feed Risers for One-Pipe Low Pressure Steam Based on A. 5. H. V. E. Research Laboratory Tests Pcpb Sob Inches A i m 2 2Y2 3 m 4 Velocity Feet Per Second Pressure Drop Ounces per 100 Ft B 14.1 17.6 20.0 23.0 26.0 29;0 31.0 32.0 C 0.68 0.66 0.66 0.57 0.54 0.48 0.44 0.39 Sq Ft Radiation D . 45 98 152 288 464 799 1144 1520 Capacity Btu per Hour E 10.961 23,765 36,860 69,840 112,520 193,600 277,000 368,000 Lb Steam per Hour F 11.3 24.5 38.0 72.0 116.0 199.8 286.0 380.0 INSTRUCTIONS FOR USING TABLE 1 1. Capacities given in Table 1 should never be exceeded on one-pipe risers. 2. Capacities are based on K-lb condensation per square foot equivalent radiation and actual diameter of standard pipe. 3. All pipe should be well reamed and free from constrictions. Fittings should be up to size. (See Tables 4 and 5). Table 2. Maximum Allowable Capacities of Up-Feed Risers for Two-Pipe Low Pressure Steam Based on A. S. H. V. E. Research Laboratory Tests Pipe Size Inches Velocity Feet per Second Pressure Drop Ounces fee 100 Ft AB C 2 -- 1 23 1.78 m 27 1.57 30 1.48 2 35 *1 2 3 1.33 m 38 1.16 3 41 0-95 m 42 0.81 4 43 0.71 Sq Ft Radiation D 40 74 151 228 438 678 1129 1548 2042 Capacity Btu per Hour E 9550 17,900 36,500 55,200 106,100 164,100 273,500 375,500 495,000 Lb Steam per Hour F 10.0 18.45 37.65 57.0 109.5 .169.4 282.2 387.0 510.5 INSTRUCTIONS FOR USING TABLE 2 1. The capacities given in this table should never be exceeded on two-pipe risers. 2. Capacities are based on K-Ib condensation per square foot equivalent radiation and actual diameter of standard pipe. 3. All pipe should be well reamed and free from constrictions. Fittings should be up to size. (See Tables 4 and 5.) 304 Chapter 16. Piping for Steam Heating Systems Table 3. Comparative Capacity of Steam Lines at Various Pitches for Steam and Condensate Flowing in Opposite Directions5* Pitch of Pipe in Inches per 10 Ft Pitch op Pipe a rn. Inches SqFt Rad. Based Btu e9 M IN. SqFt Rad. Based on 240 Btu 9) cd 1 IN. SqFt Rad. Based on 240 Btu IM IN. SqFt Rad. Based on 240 Btu 2 in. 3 m. 4 IN. Sq Ft SqFt SqFt Rad. Based Rad. Based i Rad. Based on 240 Btu on 240 Btu 1 on 240 Btu 5 m. SqFt Rad. Based on 240 Btu i 25.0 12 30.3 14 37.3 18 40.4 19 42.5 20 46.1 21 47.5 22 49.3 23 t % 45.8 12 52.6 15 63.0 17 70.0 20 7S.2 22 83.0 23 87.9 25 90.2 26 IH 104.9 18 117.2 20 133.0 23 144.5 25 154.0 27 165.0 28 172.6 29 178.2 31 IX 142.6 18 159.0 21 181.0 23 196.5 25 209.3 27 224.0 28 234.8 30 242.6 31 2 236.0 19 263.5 20 299.5 23 325.5 25 346.5 27 371.5 28 388.4 29 401.1 30 aData from American Society of Heating and Ventilating Engineers Research Laboratory. Equivalent Length of Run All tables for the flow of steam in pipes, based on pressure drop, must allow for the friction offered by the pipe as well as for the additional resistance of the fittings and valves. These resistances generally are stated in terms of straight pipe; in other words, a certain fitting will produce a drop in pressure equivalent to so many feet of straight run of the same size of pipe. Table 6 gives the number of feet of straight pipe usually allowed for the more common types of fittings and valves. In all pipe sizing tables in this chapter the length of run refers to the equivalent length of run as distinguished from the actual length of pipe in feet. The length of run is not usually known at the outset; hence it is necessary to assume some pipe size at the start. Such an assumption frequently is considerably in error and a more common and practical method is to assume the length of run and to check this assumption after the pipes are sized. For this purpose.the length of run usually is taken as double the actual length of pipe. Table 4. Per Cent Difference in Capacity for Carrying Steam and Condensate Due to Variation of Pipe Size and Smoothness* Maximum Condensation, Lb per Hour Size of pipe......... ..............................:___ Minimum Maximum Per cent variation Min. 14.00 15.20 8.6 1 In. 24.89 30.08 20.8 . 1M In. 45.42 52:08 14.7 l^In. 70.50 82.00 16.3 aData from American Society of Heating and Ventilating Engineers Research Laboratory. Table 5. Effect of Reaming Entrance to One-Inch One-Pipe Risers* Reamed entrances Squared entrances Three wheel cnfter Sinele wheel cutter Maximum Capacity o? Riser 24.7 lb per hour 23.9 lb per hour 22.2 lb per hour 19.2 lb per hour 17.6 lb per hour Per Cent Decrease 0.0 3.2 10.1 22.2 28.7 Data from American Society of Heating and Ventilating Engineers Research Laboratory. 305