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American Society of Heating and Ventilating Engineers Guide, 1932
Table 15. Pipe Sizes for Vacuum Pump Systems, where Equivalent Length of Run from
Boiler or Source of Supply to Farthest Radiator Exceeds 200 Ft.
Capacity in Sq. Ft. of Equivalent Radiation
Based on 4 oz. Total Pressure Drop
Pipe Size Inches
A
X
i
ix
1M 2
2X
3
3X
4 5
6 8
10 12
Equivalent Length op Pipe prom Boiler to Farthest Radiator, Including Main and Riser. (See Note 6.)
Supply Mam Dripped and Branches to Risers Dripped-- Steam and Condensate flowing in same direction.
100 FL
B
iii
245 380
771 1270
2326 3474
4914 9092
14,924 31,066
56,689 90,985
200 FL
c
79
173 269
546 898
1645 2457
3475 6429
10,553 21,967
40,085 64,336
300 Ft
D
*65
141 220
446 734
1342 2006
2828 5250
8618 17,935
32,730 52,530
400 Ft
E
...
56
122 190
386 635
1163 1737
2457 4546
7462 15,533
28,345 45,492
500 Ft
P
....
49
110 165
345 568
1040 1552
2196 4062
6669 13,880
25,334 40,660
600 FL
a
46
100 155
315 518
948 1419
2011 3712
6094 12,682
23,144 37,145
Maximum Capacities
Supply Risers Up-Feed
Branches to Supply Risers and Radiators Not Dripped
H
56 122 190 386 635 1129 1548 2042
___
--
--
/a
_
26
58 95
195 395
700 1150
1700 3150
___
--
__
----X
'Pipe Size Inches
Return Mains and Risers
Riser
Main K
100 FtL
X
X1
i1x.
ix
tX
800 1400
2400 3800
IX 2
8000
2 2X 13,400
2X 3
21,400
3 3X 32,000
3X 4
44,000
200 Ft
M
568 994
1704 2696
5680 9510
15,190 22,710
31,220
300 Ft.
N
462 810
1387 2195
4622 7745
12,360 18,490
25,430
400 Ft
0
400 700
1200 1900
4000 6700
10,700 16,000
22,000
500 Ft
P
358 626 1073 1698 3575 5990
9565 14,300
19,660
'600 Ft
0
326 570
976 1547
3256 5453 8710 13,020
17,910
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 connection
to be of same size as valve and trap* used. Return horizontal
runout to be ho lass
than % in.
Copyright,
1927
{American Societt or Heating and Ventilating Engineers
Heating and Piping Contractors National Association '
Not to be Reprinted With out Special Permission
156
Chapter 9--Steam Heating Systems and Pipe Sizes
INSTRUCTIONS FOR USING TABLE 15
ai. Radiator branches more than 8 ft. in length should be one size larger than shown in Column I.
2. It is not generally considered good practice to greatly exceed 1 oz. drop in pressure in each 100 ft. equivalent length of run nor to exceed 1 lb. total pressure drop in any system.
3. These tables apply where pipes are properly reamed. No allowance for defective material or workmanship have been made. (Also see Tables 7 and 8).
4. Capacities based on X 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. Mains are to be proportioned according to the equivalent length of run from the boiler or source of supply to the farthest radiators supplied by the main.
Determine equivalent lerjgth of run then use figures in corresponding Columns (B to G) for sizing the entire run.
For example: If the distance from boiler or source of supply to the farthest radiator on the longest main should be 300 ft., all mains are to be sized from Column D; if 400 ft., Column E; if 600 ft.. Column G.
Supply risers are to be proportioned according to the equivalent length of run from the boiler or source of supply to the farthest radiator on each riser. Determine the distance to the farthest radiator then use figures in corresponding Columns (B to G) for sizing each riser; providing the amount of radiation for that riser does not exceed amounts shown in Column H. Where riser capacities are found to be in excess of amounts shown in Column H, step up to necessary size indicated in that column.
For example: If the distance from the boiler or source of supply to the farthest radiator on a supply riser is 300 ft., that riser is to be sized from Column D, providing the amount of radiation does not exceed the amount shown in Column H. If the amount exceeds that in Column H, use amounts shown in Column H for sizing that entire riser.
If another riser taken from the same main as the one indicated is only 200 ft., this riser should be sized from Column C, providing the amount of radiation does not exceed that as shown in Column H.
7. For practical purposes the pipe sizes on the usual heating system may be deter mined by using the pressure drop indicated by the longest main and riser on that system, neglecting the separate computations for each separate shorter run.
8. Return mains and risers are to be proportioned according to the equivalent distance in feet, from farthest radiator to the vacuum pump; using capacities in corresponding Columns (Z. to Q) for sizing entire return riser (Column J) and return main (Column K). The return pipe sizes are conservative and are subject to revision upon the completion of pending research investigations.
9. Where it is necessary to drip a supply main, supply riser or branch to a supply riser, same should be dripped separately through a steam trap into vacuum return. Never drip a supply riser into a vacuum return, except through a steam trap.
10. Lift fittings. (See page 161).
11. Pitch of mains should be not less than X in. in 10 ft.; on horizontal branches to radiators and risers at least X in. in 10 ft.
157