Document b5ndGJkxRLag0njgK4gmKGVqg

American Society of Heating and Ventilating Engineers Guide, 1929 Table 1. Flow of Steam in Pipes p/o*/ of Sfe<r/7? if? Pipes P- oss /// Pessso/ee /// L os. c/- //ts/oc DjamTC* or P/ps /-v Tvc/tss l--Lrffcrft or P/ps /// Peer D-Wz/c/ir or 7 CuPr. orSrsAAf tV-Las. or Stxam Mtr*. , *-0.00^722(7 + irwtV -07Z,0O I PDd' 1 Ozs. 0.2X o.xo Col 7 970 jJZ l/OO 7033 7.333 P/r> 3/22 7/frxjeAiAt Cot.2 7702r//T/AL AcfutAL. P/eec ar 8' /f/rXPMAl P/r* 0/AMM7ZA So, 7+36 V c7 SrsAM Pesos, sr C7ac* * / 7.029 0.862 0.786 -70 * 7i 7330 7296 7770 -ox Col 3 r a/07 a/40 LiTf/GT/t oAp/rs ///Txsr 20 40 Col. 4 700 11 2 2. 240 7X30 /oo 2.773- /i 7.670 2.036 7.323 0.0 0.793 60 7. 270 2 3 076 2 2.067 3.3S6 3.770 03 0.77s- 30 7.720 3 3 767 2 7 226? 2788 6.709 7,3 azo/ 700 7.000 4 4.3SO 3 8 068 7373 77733 23 O.Z07 /ZO O 9/2 X 2.863 3i 3.S20 . 9887 76.702 S3 0.223 740 O 827 6 S.323 4 4.026 72730 2363/ 70.3 0.243 760 O. 79S 7 X7SX 44 4. SO6 7X947 32734 /S3 0.270 780 0.74/ 3 .7X2 X X.047 20.006 43.7/9 ZO. 3 0 79 Zoo O. 7/0 to 773 6 6o6S 23.306 77762 303 0.326 2X0 0.632 /2 7X34 7 7023 38 723 706.278 40.3 O.SS8 300 O.J73 74 3.733 0 76 3.7oo 9 7. TO7 So 027 729.382 3.94/ 2736 2o/. 833 So. 3 60.3 0383 0.4/3 3SO 400 O.S33 O. XOO 20 24 28 32 40 28 30 760 9727 70 70.6XX /2 7/.X09 74 70.020 76 834 272392 7X3 72.000 773.078 437.SOS \ 73.2SO 73733c 366.6f6 700.3 /2S.3 0.432 O.S07 O.XX7 4X0 *0477 xoo 0.447 600 0.407 72 304 /J. 776 72069 794X4 27372 76 7S.2SO 782626 376.37c . 7SO. 3 Column 1 X 2 X 3 X .4 lb. of steam /7X.3 straight pipe for a given condition. Zoo. 3 Example.--1 oz. drop -- 2 in. pipe -- 1.3 lb. press. -- 100 ft. equivalent length: 0.603 0.64X csss 2.175 X 3.710 X 0.201 X 1 - 1.6219 lb. per min. TOO 300 ?oo 7000 7200 0.378 0.3X4 0 333 0.3/6 0.289 320 430 33 9o3 27-6T2 Table 1 does not allow for entrained'water in low-pressure steam, condensation, in covered pipe and roughness in com mercial pipe as found in practice. 7X00 0 2X3 . 2000 0.224 lb. per sq. in. gage = 2.04 in. Vacuum. Mercury Column. 86 Chapter III--Steam Heating Systems and Piping STEAM DISTRIBUTION The piping for steam, distribution will be divided into two classes: (1) transmission mains, (2) service piping. Transmission mains are defined as those that convey steam for a con siderable distance either through or between buildings such as in district heating plants. In this type the steam is usually generated and trans mitted to the building under high pressure where by means of a pressure reducing valve it is lowered to the pressure required in the building. The velocities of flow used in the transmission mains are limited by the available or allowable drop in pressure. See Table 2 for capacity of pipes at various pressures. Service piping is defined as that which conveys the steam and con densate in the building, starting either at the boiler or other source of supply and comprising of the mains, branches, risers, radiator connections and return piping. This part of the system is usually low pressure arid the pipe sizes are larger, as the velocity of the steam is lower and the available or allowable drop in pressure is small. See Tables 10 to 18 for the service pipe sizes for various systems. STEAM HEATING PIPE SIZES Generally, in using tables for steam heating pipe sizes, it is difficult to determine the length of run upon which they are based. Usually some allowance is made for one or more such items as: condensation in the pipe, equivalent length of pipe, for fittings, valves, etc., but it is generally difficult to determine what factors have been allowed for, and what percentage of allowance has been made. In compiling the Tables 1-18 and other data for The Guide, 1929, every attempt has been made to eliminate such indefinite and conflicting factors. The principal factors upon which the determination of pipe sizes for steam heating depends, are: 1. The equivalent length of the run from the boiler, or source of steam supply, to the farthest heating unit. 2. The total pressure drop, which may be allowed, between the source of supply and the end of the return system. 3. The maximum velocity of steam allowable for quiet and dependable operation of the system. 4. Unusual conditions in the building to be heated. Length oj Run The length of run must not only include the actual linear feet of straight pipe, but .also the proper allowance for fittings, valves and other items which cause drop in pressure. (See Table 4.) Pressure Drop Theoretically there are several factors to be considered such as initial pressure and the pressure required at the end of the line,-but it is most important that (1) the total pressure drop does not exceed the initial pressure of the system, (2) that the pressure drop is not so great as to 87 l s