Table 1: Maximum Capacity of Schedule 40 Pipe in CFH For Natural Gas Pressures of ½ psig or Less
Length |
| 0.3 Inch w.c. Pressure Drop |
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| 0.5 Inch w.c. Pressure Drop |
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[Feet] | ½ |
| ¾ | 1 |
| 1¼ | ½ |
| ¾ | 1 |
| 1¼ |
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10 | 132 |
| 278 | 520 |
| 1,050 | 175 |
| 360 | 680 |
| 1,400 |
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20 | 92 |
| 190 | 350 |
| 730 | 120 |
| 250 | 465 |
| 950 |
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30 | 73 |
| 152 | 285 |
| 590 | 97 |
| 200 | 375 |
| 770 |
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40 | 63 |
| 130 | 245 |
| 500 | 82 |
| 170 | 320 |
| 660 |
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50 | 56 |
| 115 | 215 |
| 440 | 73 |
| 151 | 285 |
| 580 |
60 | 50 |
| 105 | 195 |
| 400 | 66 |
| 138 | 260 |
| 530 |
70 | 46 |
| 96 | 180 |
| 370 | 61 |
| 125 | 240 |
| 490 |
80 | 43 |
| 90 | 170 |
| 350 | 57 |
| 118 | 220 |
| 460 |
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90 | 40 |
| 84 | 160 |
| 320 | 53 |
| 110 | 205 |
| 430 |
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100 | 38 |
| 79 | 150 |
| 305 | 50 |
| 103 | 195 |
| 400 |
Table 2: Equivalent Length of Fittings
Fitting |
| Nominal Pipe Size |
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½ |
| ¾ | 1 |
| 1¼ | |
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45° Ell | 0.7 |
| 1 | 1.2 |
| 1.6 |
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90° Ell | 1.6 |
| 2.1 | 2.6 |
| 3.5 |
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Tee (As Elbow) | 3.1 |
| 4.1 | 5.2 |
| 6.9 |
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This piping is to be supplied by the installer and must include a trap, a ground joint union and a manual shutoff valve upstream of the gas control assembly outside of the jacket when codes require, see Figure 1. A pipe thread compound resistant to the action of liquefied petroleum gases should be applied to all threaded joints in the gas piping. Pressure testing of the Gas Supply Piping Boiler and its connections is required before placing the boiler in operation.
The boiler and shutoff valve must be disconnected from the gas supply piping system during any pressure testing at pressures greater than ½ psig (3.5kPa).
The boiler must be isolated from the gas supply piping system by closing its individual manual shutoff valve during any pressure testing of the gas supply piping system at pressures equal to or less than ½ psig (3.5kPa).
Recommended sizing of gas supply piping to boiler for natural gas - shall be such as to provide the required supply of gas without undue loss of pressure between meter and the boiler. Gas supply piping should be sized in accordance with the Tables 1, 2 and 3. The following shall be taken into account:
Table 3: Specific Gravity Correction Factors for Natural Gas
Specific | Correction | Specific | Correction |
Gravity | Factor | Gravity | Factor |
0.50 | 1.10 | 1.30 | 1.07 |
0.55 | 1.04 | 1.40 | 1.04 |
0.60 | 1.00 | 1.50 | 1.00 |
0.65 | 0.96 | 1.60 | 0.97 |
0.70 | 0.93 | 1.70 | 0.94 |
0.75 | 0.90 | ||
0.80 | 0.87 |
A.Allowable loss of pressure to assure a burner manifold pressure of 3½" (8.9cm) water for natural gas.
B.Supply of gas to be provided in cubic feet.
C.Length of piping and number of fittings.
D.Specific gravity of gas.
E.Correction factor for specific gravity.
9.BOILER PIPING
CAUTION
Failure to properly pipe boiler may result in improper operation and damage to boiler or building.
A.Clearances - Hot water pipes do not require clearance from combustible construction.
B.Install drain valve and safety relief valve as shown in Figures 1 and 3. Note - Safety relief valve must be in vertical position.
C.Pipe safety relief valve discharge to floor.
