RBI SPECTRUM Series - Gas Supply Piping; Gas Pipe Capacity

Finned copper tube gas boilers & water heaters – Boiler Manual
17
GAS SUPPLY PIPING
Check the boiler/water heater rating plate
to make sure that the boiler/water heater is
for the type of gas that will be used. If it isn’t, do not
connect the boiler/water heater to the gas supply.
Gas supply piping must be in accordance with the
National Fuel Code, ANSI Z223.1-latest revision
or applicable provisions of the local building codes.
Canadian Installations must comply with CAN/CGA
B149.1 or .2 Installation Code. Failure to comply with
this warning can result in extensive property damage,
severe personal injury or death!
e Spectrum boiler/water heaters come from the factory ready
to be piped to the gas supply. If for any reason the boiler/water
heater is not for the type of gas available at the installation site, call
the nearest RBI representative to resolve the problem.
A minimum gas supply pressure of 5 in, 127 mm WC
natural or 12 in, 305 mm WC propane and maximum
gas supply pressure of 14 in, 356 mm WC natual or
propane, must be available at the safety shuto valve
inlet with the unit(s) operating.
Table 10 should be used to ensure that the gas supply piping is
sized properly. If more than one appliance is supplied by the same
supply pipe, the piping must be sized based on the maximum possible
demand. Do not neglect the pressure drop due to pipe ings. Table
10 should be used in conjunction with Table 11 to ensure that the
gas supply piping has the capacity to meet the demand.
Table 10 Gas Pipe Capacity
Maximum pipe capacity in ft
3
/hr based on 0.60 specic gravity gas
at a pressure of 0.5 psig or less and a 0.3" WC pressure drop.
Nominal
Iron Pipe
Size
Pipe length in feet
10 20 30 40 50 60 80 100 150
Maximum gas volume of pipe, (ft
3
/hr)
3/4" 278 190 152 130 115 105 90 79 64
1" 520 350 285 245 215 195 170 150 120
1 1/4" 1050 730 590 500 440 400 350 305 250
1 1/2" 1600 1100 890 760 670 610 530 460 380
2" 3050 2100 1650 1450 1270 1150 990 870 710
2 1/2" 4800 3300 2700 2300 2000 1850 1600 1400 1130
3" 8500 5900 4700 4100 3600 3250 2800 2500 2000
4" 17,500 12,000 9700 8300 7400 6800 5800 5100 4100
Note: Multiply the gas volume by 0.62 for propane ow capacity in ft
3
/hr.
Multiply the propane ow capacity by 2500 Btu/ft
3
to determine
the propane Btu/hr capacity for a given pipe size and length.
Table 11 Equivalent Pipe Length
Nominal
Iron Pipe
Size
Type of pipe tting
90˚ Elbow Tee
1
Gate Valve
2
Gas Cock
2
Equivalent pipe length, (ft)
1" 2.6 5.2 0.6 1.5
1 1/4" 3.5 6.9 0.8 1.9
1 1/2" 4.0 8.0 0.9 2.3
2" 5.2 10.3 1.2 3.0
2 1/2" 6.2 12.3 1.4 3.7
3" 7.7 15.3 1.8 4.5
4" 7.7 15.3 1.8 4.5
Notes: 1. For ow through branch.
2. For ow at full open.
Figure 10 depicts the proper way to connect the boiler/water heater
to the gas supply piping. e manual shut-o valve MUST be installed
in the supply piping. It should be installed 5 , 1.5 m above the
oor where required by local codes. Provide a sediment trap at the
boom of the vertical section of the gas supply pipe upstream of
the gas controls.
A ground joint union should be installed between the boiler gas
controls and the supply piping. Each of these items are needed to
ensure long life and ease of servicing. Always use a pipe sealant that
is suitable for use with LP gas.
Figure 10 Gas Supply Piping
Always use a wrench on the gas valve body when
making gas connections to it. Never over-tighten the
piping entering the gas valve body or gas valve failure
may result!
RIOM-47