Rheem RGFG Installation Instructions Manual page 32

TABLE 9
NATURAL GAS PIPE CAPACITY TABLE (CU. FT./HR.)
Capacity of gas pipe of different diameters and lengths in cu. ft. per hr. with pressure drop of 0.3 in. and
specific gravity of 0.60 (natural gas).
Nominal
Iron Pipe
Size, Inches
1/2
3/4
1-1/4
1-1/2
After the length of pipe has been determined, select the pipe size which will provide the minimum cubic
feet per hour required for the gas input rating of the furnace. By formula:
The gas input of the furnace is marked on the furnace rating plate. The heating value of the gas
(BTU/FT3) may be determined by consulting the local natural gas utility or the LP gas supplier.
TABLE 10
LP GAS PIPE CAPACITY TABLE (CU. FT./HR.)
Maximum capacity of pipe in thousands of BTU per hour of undiluted liquefied petroleum gases (at 11
inches water column inlet pressure).
(Based on a Pressure Drop of 0.5 Inch Water Column)
Nominal
Iron Pipe
Size, Inches
1/2
3/4
1-1/4
1-1/2
Example (LP): Input BTU requirement of unit, 150,000
LP COPPER TUBE SIZING TABLE
Sizing between single or second stage (low pressure) regulator and appliance. Maximum capacity of pipe in thousands of BTU
per hour of undiluted propane gases (at 11" w.c. setting).
Outside Diameter
Copper Tubing,
Type L
3/8"
1/2"
5/8"
3/4"
7/8"
32
10 20
132 92
278 190
1 520 350
1,050 730
1,600 1,100
Cu. Ft. Per Hr. Required =
10 20 30 40
275 189 152 129
567 393 315 267
1 1,071 732 590 504
2,205 1,496 1,212 1,039
3,307 2,299 1,858 1,559 1,417 1,275 1,181 1,086 1,023
2 6,221 4,331 3,465 2,992 2,646 2,394 2,205 2,047 1,921 1,811 1,606 1,496
Equivalent length of pipe, 60 ft. = 3/4" IPS required.
10 20 30
49 34 27
110 76 61
206 141 114
348 239 192
536 368 296
Length of Pipe, Feet
30 40 50 60
73 63 56 50
152 130 115 105
285 245 215 195
590 500 440 400
890 760 670 610
Gas Input of Furnace (BTU/HR)
Heating Value of Gas (BTU/FT
Length of Pipe, Feet
50 60 70 80 90
114 103 96 89 83
237 217 196 182 173
448 409 378 346 322
913 834 771 724 677
Length of Pipe, Feet
40 50 60 80
23 20 19 16
52 46 42 36
97 86 78 67
164 146 132 113
253 224 203 174
70 80
46 43
96 90
180 170
370 350
560 530
3 )
100 125 150
78 69 63
162 146 132
307 275 252
630 567 511
976 866 787
100 125 150
14 11 10
32 28 26
59 52 48
100 89 80
154 137 124