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Table 3 — Maximum Gas Flow Capacity*
NOMINAL
IRON PIPE,
SIZE
(in.)
INTERNAL
DIAMETER
(in.)
LENGTH OF PIPE, FT†
10 20 30 40 50 60 70 80 90 100 125 150 175 200
1
⁄
2
.622 175 120 97 82 73 66 61 57 53 50 44 40 — —
3
⁄
4
.824 360 250 200 170 151 138 125 118 110 103 93 84 77 72
1 1.049 680 465 375 320 285 260 240 220 205 195 175 160 145 135
1
1
⁄
4
1.380 1400 950 770 600 580 530 490 460 430 400 360 325 300 280
1
1
⁄
2
1.610 2100 1460 1180 990 900 810 750 690 650 620 550 500 460 430
*Capacity of pipe in cu ft of gas per hr for gas pressure of 0.5 psig or less. Pressure drop of 0.5-in. wg (based on
a 0.60 specific gravity gas). Refer to Table C-4, National Fire Protection Association NFPA 54.
†This length includes an ordinary number of fittings.
SUPPLY DUCT OPENING RETURN DUCT OPENING
Fig. 16 — Supply and Return Duct Openings
Fig. 17 — Lance Location for Vertical Duct
Opening Cover
Fig. 18 — Vertical Duct Cover Removed
Fig. 19 — Removal of Vertical Discharge
Opening Cover
17