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HEATING VENTILATING AIR CONDITIONING GUIDE 1940
Table 1. Flow of Steam in Pipes
P -- loss in pressure in pounds.
d = inside diameter of pipe in inches. L = length of pipe in feet. D = weight of 1 cu ft of steam. W = pounds of steam per hour.
W = 5220
P = 0.0000000367 ( 1 +
Pressure Loss
IN
Ounces
COlu 1
Pipe Size
5220Vvio Nomina
Actual Internal
Diameter
Internal
Area or
- Pipe
Sq Inches
Col. 2
Col. 3
PkS8.
BT
Gage
VT
Length
Of PtPB
IN
Feet
Cou 4
v?
0.25 65.28 i
1.049
0.864 0.536 -1.0a 0.187
20 2.240
0.50 92.28
1.380
1.496 1.178 -0.5a 0.190
40 1.580
1.00 130.5
i H . 1.610
2.036 1.828 0.0 0.193
60 1.290
2
184.6 2
2.067
3.356 3.710 . 0.3 0.195
80 1.120
3
226.0 m 2.469
4.788 6.109 1.3 .0.201
100 1.000
4
261.0 3
3.068
7.393 11.183 2.3 0.207 120 0.912
5
291.8 3Vi 3.548
9.87 16.705 5.3 0.223 140 0.841
6
319.7 4
4.026 12.730 23.631 10.3 0.248 .160 0.793
7 345.3
4.506 15.947 32.134 15.3 0.270 180 0.741
8
369.1 5
5.047 20.006 , .43.719 20.3 0.290 200 0.710
10
412.7 6
6.065 28.886 . 71'. 762 30.3 0.326 250 0.632
12 452.0 7 7.023 38.743. 106.278 40.3 0.358 . -300 0.578
14 488.3 8 7.981 50.027 149.382 -50.3- ,0.388 350 0.538
. 16 .
522.0 9
8.941 62.786 201.833 60.3 0.4i5 :. 400. 0.500
20
583.6 10
10.020 78.854 272.592 75.3 0.452 450 > 0.477
.24 . 639.3 12 , 12.000 113.098, .437.503 100,3 0.507 500 0.447
' 28
690.5 14
13.250 137.880 566.693 125.3 0.557 . 600 0.407
'. 32
738.2 16
15.250 182.655 816.872 150.3 0.603 700 0.378
40 48 80 160 320 480
825.4 904.1 1167.2 1650.7 2334.5. 2859.1
Column I X 2 X 3 X 4 * lb of steam 175.3
per hour that will flow through a straight
pipe for a given condition.
200.3
Example 1: 1 oz drop -- 2 in. pipe
-- 1.3 lb press. -- 100 ft equivalent length:
0.645 0.685
130.5 X 3.710 X 0.201 X 1 97.2 lb per hour 97.2 X 4b = 388.8 sq ft equivalent radiation
T Table 1 does not allow for.entrained water.in low-j>ressure steam, condensation in covered pipe and roughness n commercial pipe as found in practice.
800 900 1000 1200 1500 2000
.0.354 0.333 0.316 0.289 0.258 0.224
Pounds per square inch gage => 2.04 in. Vacuum, Mercury Column. bThe factor 4 is the approximate equivalent in square feet of steam radiation of 1 lb of steam per hour.
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CHAPTER 16. PIPING FOR STEAM HEATING SYSTEMS
locations may be different than those which exist for appreciable periods at other locations and which under constant pressure may have conditions that are approximately the same. In designing piping it is of especial imporance t0 arrange the system to preclude trouble caused by such pressure differences. The systems, which readily release the air permit uniform pressures to be attained in much shorter time intervals than those which are sluggish. Results are given in Fig. 1 from investigations1 to determine the rate of condensate and air return from a two-pipe gravity heating system. Variations in the steam pressure during the warming up period when the rate of air elimination and condensation is high are clearly indicated in these curves.
It is evident that the condensation flow during the initial w;arming up
period reaches a peak which' is greater than the constant condensation rate which is eventually reached when the pressure becomes uniform. Moreover, the peak condensation rate is obtained when the system steam pressure is lower than that existing during a period of constant condensing rate. It will also be noted that the peak rate of air elimination does not coincide with the higher condensing rate.
STEAM FLOW The rate of flow of dry steam or steam with a small amount of water flowing in the same direction is in accordance with the general laws of gas flow and is a function of the length and diameter of the, pipe, the density of the steam, and the pressure drop through the pipe. This relationship has been established by Babcock in the formula given at the top of Table 1. In Columns 1, 2, 3, and 4 of this table, the numerical values of the factors for different pressure losses, pipe diameters, steam densities and lengths of pipe have been worked out in convenient form so that the steam flowing in any pipe may be calculated by multiplying together the proper factors in each column as shown in the example at the bottom of the table.
A.S.H.V.E. Research Report No. 954--Condensate and Air Return in Steam Heating Systems, by F. C. Houghten and J. L. Blackshaw (A.S.H.V.E. Transactions. VoI. 39, 1933, p. 199).
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