TO TRAP ANY DIRT OR FOREIGN MATERIAL IN THE GAS SUPPLY LINE, A DIRT LEG (SOMETIMES CALLED DRIP LEG or sediment trap) MUST BE INCORPORATED IN THE PIPING, see Figure 1 on page 6. The dirt leg must be readily accessible and not subject to freezing conditions. INSTALL IN ACCORDANCE WITH RECOMMENDATIONS OF SERVING GAS SUPPLIERS. (Refer to National Fuel Gas Code, ANSI Z223.1 or
To prevent damage, care must be taken not to apply too much torque when attaching gas supply pipe to the gas valve gas inlet.
Fittings and unions in the gas line must be the metal to metal type.
Apply joint compounds (pipe dope) sparingly and only to the male threads of pipe joints. Do not apply compound to the first two threads. Use compounds resistant to the action of liquefied petroleum gases.
THE BOILER AND ITS GAS CONNECTIONS MUST BE LEAK TESTED BEFORE PLACING THE BOILER IN OPERATION. Use soap and water solution or other material acceptable for the purpose in locating gas leaks. DO NOT USE MATCHES, CANDLES, FLAME OR OTHER SOURCES OF IGNITION FOR THIS PURPOSE.
DISCONNECT THE BOILER AND ITS MAIN MANUAL GAS SHUTOFF VALVE FROM THE GAS SUPPLY PIPING SYSTEM DURING ANY PRESSURE TESTING OF THE GAS SUPPLY SYSTEM OVER 1/2 PSIG (3.5kPa). THE GAS SUPPLY LINE MUST BE CAPPED WHEN NOT CONNECTED TO THE BOILER.
THE BOILER MUST BE ISOLATED FROM THE GAS SUPPLY PIPING SYSTEM BY CLOSING ITS MAIN MANUAL GAS SHUTOFF VALVE DURING ANY PRESSURE TESTING OF THE GAS SUPPLY PIPING SYSTEM AT TEST PRESSURES EQUAL TO OR LESS THAN 1/2 PSIG (3.5kPa).
PURGING AND SIZING
Gas line purging is required with new piping or systems in which air has entered.
CAUTION
PURGING SHOULD BE PERFORMED BY PERSONS EXPERIENCED IN THIS TYPE GAS SERVICE TO AVOID RISK OF FIRE OR EXPLOSION. PURGE DISCHARGE MUST NOT ENTER CONFINED AREAS OR SPACES WHERE IGNITION CAN OCCUR. THE AREA MUST BE WELL VENTILATED AND ALL SOURCES OF IGNITION MUST BE INACTIVATED OR REMOVED.
1.CORRECT GAS
Make sure the gas on which the boiler will operate is the same as that specified on the boiler rating plate. Do not install the boiler if equipped for a different type gas — consult your supplier.
2A. SIZING GAS SUPPLY LINE (For single boiler installations and for installations of multiples of two or three of same size boilers).
Use table 7, or CAN/CSA B149.1 (current edition) to size iron pipe or equivalent gas supply line. Table 7 is based on a pressure drop of 0.3 inches of water and a specific gravity of 0.60 approximately that of natural gas. (LP gas has an S.G. of about 1.53). If the service pressure is five inches water column or less, use one pipe size larger in order to minimize pressure drop in the line.
TABLE 7.
MAXIMUM CAPACITY OF PIPE IN CUBIC FEET OF GAS PER
HOUR (BASED UPON A PRESSURE DROP OF 0.3 INCH WATER COLUMN AND 0.6 SPECIFIC GRAVITY GAS)
Distance |
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| Nominal Iron Pipe Size (Inches) |
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from Gas |
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Meter |
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1/2 | 3/4 | 1 | 1 1/4 | 1 1/2 | 2 | 2 1/2 | 3 | 4 | |||
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10 | (3) | 132 | 278 | 520 | 1,050 | 1,600 | 3,050 | 4,800 | 8,500 | 17,500 | |
20 | (6) | 92 | 190 | 350 | 730 | 1,100 | 2,100 | 3,300 | 5,900 | 12,000 | |
30 | (9) | 73 | 152 | 285 | 590 | 890 | 1,650 | 2,700 | 4,700 | 9,700 | |
40(12) | 63 | 130 | 245 | 500 | 760 | 1,450 | 2,300 | 4,100 | 8,300 | ||
50 (15) | 56 | 115 | 215 | 440 | 670 | 1,270 | 2,000 | 3,600 | 7,400 | ||
60 (18) | 50 | 105 | 195 | 400 | 610 | 1,150 | 1,850 | 3,250 | 6,800 | ||
70 (21) | 46 | 96 | 180 | 370 | 560 | 1,050 | 1,700 | 3,000 | 6,200 | ||
80 (24) | 43 | 90 | 170 | 350 | 530 | 990 | 1,600 | 2,800 | 5,800 | ||
90 (27) | 40 | 84 | 160 | 320 | 490 | 930 | 1,500 | 2,600 | 5,400 | ||
100 | (30) | 38 | 79 | 150 | 305 | 460 | 870 | 1,400 | 2,500 | 5,100 | |
125 | (38) | 34 | 72 | 130 | 275 | 410 | 780 | 1,250 | 2,200 | 4,500 | |
150 | (45) | 31 | 64 | 120 | 250 | 380 | 710 | 1,130 | 2,000 | 4,100 | |
175 | (53) | 28 | 59 | 110 | 225 | 350 | 650 | 1,050 | 1,850 | 3,800 | |
200 | (60) | 26 | 55 | 100 | 210 | 320 | 610 | 980 | 1,700 | 3,500 | |
*The heating value of Natural Gas is approximately 1,050 Btu/Ft.3. Propane (LP) Gas has a heating value of approximately 2,500 Btu/Ft3. 1 cu. meter=35.31 cu. feet.
Where it is necessary to use more than the average number of pipe fittings i.e. elbows, tees, and valves in gas supply line, use a pipe larger than specified to compensate for increased pressure drop.
2B. SIZING GAS SUPPLY LINE (For multiples of over three boilers of same size or for multiple installations of two or more mixed sizes).
Capacities in cubic feet per hour of 0.60 specific gravity gas for different sizes and lengths are shown in table 7. No additional allowance is necessary for an ordinary number of fittings.
Applications of the gravity factor converts the figures given in table 7 to capacities with another gas of different specific gravity. Such application is accomplished by multiplying the capacities given in table 7 by the multipliers shown in table 8 on page 22.
To determine the size of each section of gas piping in a system within the range of table 7 proceed as follows:
•Determine the gas demand of each appliance to be attached to the piping system. When table 7 is to be used to select the piping size, calculate the gas demand in terms of cubic feet per hour for each piping system outlet. The gas demand for an appliance can be found by dividing its heat input rate by the gas’s heating value.
•Obtain or determine the length of piping from the gas meter or service regulator to the appliance(s).
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