Gas Pipe Sizing Tables (Referenced From 2012 National Fuel Gas Code) - Navien NCB-180 Service Manual

6. Re-open the manual gas valve and check for leaks.
7. Open multiple fixtures that have high flow rates, such as
bathtub and shower faucets, to allow the boiler to operate
up to its maximum firing rate.

4.2.1 Gas Pipe Sizing Tables (Referenced from 2012 National Fuel Gas Code)

These tables are for reference only. Please consult the gas pipe manufacturer for actual pipe capacities.
Maximum Natural Gas Delivery Capacity
in Cubic Feet (ft 3 ) per Hour (0.60 Specific Gravity; 0.5" WC Pressure Drop). Contact your gas supplier for BTU/ft
BTU/ft3 for simplified calculations. This table is recommended for supply pressures less than 6" WC.
Length (including fittings)
Pipe
10' 20'
Size
(3m) (6m)
3/4"
360 247
1"
678 466
1 1/4"
1,390 957
1 1/2"
2,090 1,430
2"
4,020 2,760
2 1/2"
6,400 4,400
3"
11,300 7,780
4"
23,100 15,900
24 NCB Service Manual
30' 40' 50'
(9m) (12m) (15m)
199 170 151
374 320 284
768 657 583
1,150 985 873
2,220 1,900 1,680
3,530 3,020 2,680
6,250 5,350 4,740
12,700 10,900 9,660
8. When the boiler reaches its maximum firing rate, check the
inlet gas pressure reading on the manometer. The gas
pressure must fall within the proper operating range
indicated in the previous page and also in the
specifications on page 17.
60' 70' 80'
(18m) (21m) (24m)
137 126 117
257 237 220
528 486 452
791 728 677
1,520 1,400 1,300
2,430 2,230 2,080
4,290 3,950 3,670
8,760 8,050 7,490
3 ratings. Use 1,000
90' 100' 125'
(27m) (30m) (38m)
110 104 92
207 195 173
424 400 355
635 600 532
1,220 1,160 1,020
1,950 1,840 1,630
3,450 3,260 2,890
7,030 6,640 5,890
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