Document 3wndjBKRrGLmD39bMqM8K0X6

American Society of Heating and Ventilating Engineers Guide, 1931 Solution: From Table 2 it is found that the capacity of a 100 ft. 4 pipe with 1 lb. initial pressure and 2 oz. pressure drop, is 3,475 sq., Multiplying this value by 0.841 the constant for a 140 ft. length as gjVgg in Table 3 gives 2,922 the capacity for the given conditions. Example: What is the capacity of a 140 ft. 4 in. pipe with 2 lb. initial^ pressure and a pressure drop of 2 oz.? Solution: From Table 2 find 3,475, the capacity of the 4 in. pw with 1 lb. initial pressure and 2 oz. pressure drop. Multiplying 3,475 by 1.03 the constant found in Column 2, Table 3, for 2 lb. initial pressure' and this by 0.841 the constant found under Column B, Table 3, the constant for 140 ft. length all as given in Table 3 gives 3,010 as the capacity of the 4 in. pipe with 2 lb. initial pressure and a pressure drop of 2 oz. in the 140 ft. length. Should lengths other than those given in Column A, Table 3, and under length of pipes in feet in Table 1 be desired the constant may be obtained from the formula in Column 4, Table 1, and used the same as the con stants from Table 3. Example: What would be the constant for 2,500 ft. of pipe to be used either in Tables 1 or 3? MSolution: The I 100 2,500 = 0.2 or the constant to be used. In determining the length of pipe used in any system, the actual length t must be increased for the various fittings and valves, in determining the 1 equivalent length before applying any of the tables given. Gate valves are recommended in all cases where service calls for the valve to be either entirely closed or open. They should never be used for throttling. Angle and globe valves should be used for throttling, such ' as the by-pass valve in a pressure-reducing outfit. . Table 4 gives the allowance for fittings in feet of pipe to be added to 1 the actual length of run to obtain the equivalent length. | SYSTEMS OF STEAM HEATING The choice of air-vent one-pipe, two-pipe, vapor or vacuum return line ij systems depends upon the requirements as to first cost, convenience, quality of service and local conditions. Theoretically, air-vent one and two-pipe and vapor and vacuum Return line systems are substantially ona par as to heating efficiency; that is to say, the major portion of the heat delivered is, or should be, dissipated by the heating unit. It is essential that any system, circulate steam uniformly throughout the entire installation, as too often certain defective features of a system will require that heat be kept on longer or to a greater degree than would otherwise be required uniformly and satisfactorily to heat the building. This will result in waste and overheating. The one important thing to be remembered in connection with all systems is that they shall circulate steam freely and uniformly to the heating units arid shall remove and return the condensation noiselessly. The following should be kept in mind in laying out ariy type of system: 1. The initial pressure should be kept as low as possible, not exceeding 5 lb. gage. 154 Col. A CoLB 0.92 1.00 1.03 1.11 1.24 1.35 1.45 1.63 1.79 1.94 2.08 2.26 2.54 2.79 3.02 3.23 3.44 20 40 60 80 100 120 140 160 180 200 250 300 350 400 450 500 600 700 800 900 1000 1400 2.240 1.580 1.290 1.120 1.000 0.912 0.841 0.793 0.741 0.7100.632 0.578 0.538 0.500 0.477 0.447 0.407 0.378 0.354 0.333 0.316 0.267 Length in Feet of Pipe to be Added to Actual Length of Run-- LllflUJn _ ___/1.________ . r oix I DMr.rn SUB OF PlPB Inches St'd. Elbow Side Outlet Tee Gate Valve Globe Valve Ancle Valve Length in Feet to be Added in Run ; 2 iVt 3 3H 4 5 6 7 g 9 10 12 14 5 16 7 20 10 26 12 31 14 35 18 44 22 50 26 55 31 63 35 69 39 76 47 90 53 105 2 18 9 3 25 12 3 33 16 4 39 19 5 45 22 7 57 28 9 70 32 10 82 37 12 94 42 13 105 47 15 118 52 18 140 63 20 160 | 72 Example of length in feet of pipe to be added to actual length of run. neAsmeo lehsth. - at'.-o' U-------- 13E~0"__ , ^ OATS VALfE. 5*0' r \ 4-4`LB0WS. - M-0 --------------V I EQl/tYALEHT LEHSTH - t93'-Q` 155