II Gas piping
Supply pipe sizing
Connect gas piping to boiler
Table 1
Gas supply pipe capacities
1.Size natural gas piping from Table 1. Size piping to provide proper inlet pressure to gas valve when operating at rated input.
a.Inlet gas pressure to manual main
b.If pressure to gas valve exceeds 13" W.C., install 100%
c.To obtain approximate cubic feet per hour, divide input (Btu/hr) by 1000.
2.Size gas piping considering:
a.Diameter and length of gas supply piping.
b.Number of fittings.
c.Maximum gas consumption (including any possible future expansion).
d.Allowable pressure drop from gas meter to boiler. For pressure drops, see ANSI Z233.1 latest edition. Canadian installations must comply with B149.1 or B149.2 Installation Code.
3.Remove knockout disc from jacket panel side to which gas supply will be piped.
4.Follow good piping practices.
5.Pipe joint compound (pipe dope) must be resistant to corrosive action of liquefied petroleum gases. Apply sparingly only to male threads of pipe joints.
6.Install drip leg at inlet of gas connection to boiler. Where local code/utility requires, extend drip leg to floor.
7.Install ground joint union when required for servicing.
8.Support piping by hangers, not by boiler or its accessories.
9.Purge all air from supply piping.
10.Before operating boiler, check boiler and its gas connections for leaks.
Do not check for gas leaks with an open flame - use bubble test. Failure to use bubble test or check for leaks can cause severe personal injury, death or substantial property damage.
a.Close manual main
b.Disconnect boiler and gas valve from gas supply piping during any pressure test greater than 13" W.C.
11.In Canada — manual main
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| Pipe length, feet * |
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PIPE |
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| (Natural gas capacities given in MBH) |
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| (Specific Gravity 0.60 @ Pressure Loss of 0.30" W.C.) |
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SIZE |
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| 10 | 20 | 30 | 40 | 50 | 75 | 100 | 150 |
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1 1/4" | 1,050 | 730 | 590 | 500 | 440 | 360 | 305 | 250 |
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1 1/2" | 1,600 | 1,100 | 890 | 760 | 670 | 545 | 460 | 380 |
2" | 3,050 | 2,100 | 1,650 | 1,450 | 1,270 | 1,020 | 870 | 710 |
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2 1/2" | 4,800 | 3,300 | 2,700 | 2,300 | 2,000 | 1,650 | 1,400 | 1,130 |
3" | 8,500 | 5,900 | 4,700 | 4,100 | 3,600 | 2,900 | 2,500 | 2,000 |
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4" | 17,500 | 12,000 | 9,700 | 8,300 | 7,400 | 6,000 | 5,100 | 4,100 |
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*Include measured length of gas supply piping and allowance in feet for number and size of fittings.
Part Number | 3 |
