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GAS PIPING
A . GENERAL
1. All fuel piping to the boiler is to be in accordance
with local codes. In the absence of local regulations
refer to the National Fuel Gas Code, ANSI
Z223.1/NFPA 54.
2. Size and install piping to provide a supply of gas
sufficient to meet the maximum demand of all
appliances supplied by the piping.
B. FUEL LINE SIZING
1. The rate of gas to be provided to the boiler can be
determined by the following:
Obtain the gas heating value from the gas supplier.
2. As an alternative use Table 4.1 which uses typical
heating values for natural gas and liquefied
petroleum (LP) gas.
3. Table 4.2 shows the maximum flow capacity of
several pipe sizes based on 0.3" of pressure drop.
a. The values shown are based on a gas specific
gravity of 0.60 (Typical for natural gas).
b. Multiply the capacities listed by the factors
indicated in Table 5.3 for gas with a specific
gravity other than 0.60 to obtain the corrected
capacity.
4. The gas piping to the boiler must be a minimum of
3/4" pipe. The boiler is supplied with a 3/4" NPT x
1/2" NPT bell reducer. Do not remove the reducer.
5. Size and install the gas supply piping for no more
than 0.5 inches of water pressure drop between the
gas regulator and the boiler.
C. GAS SUPPLY PIPING INSTALLATION
1. Do not install any piping directly over or in front of
the boiler. Locate the drop pipe adjacent to the
boiler.
4. GAS PIPING
Boiler Input Rate
Gas Heating Value
Input Rate
(
ft
³
/
hr
)
=
(
Btu
/
hr
)
(
Btu
/
ft
³
)
Boiler
Model
Gas Input Rate* (ft
³
/hr)
Natural Gas LP Gas
PI-T50 50 20
PI-T80 80 32
PI-80 80 32
PI-140 140 56
PI-199 199 79
*Natural gas input rates are based on 1000 Btu/ft
³
, LP
input rates are based on 2500 Btu/ft
³
.
Pipe
Length
(Feet)
3/4" NPT
Pipe
1" NPT
Pipe
1-1/4"
NPT
Pipe
1-1/2"
NPT
Pipe
10 278 520 1,050 1,600
20 190 350 730 1,100
30 152 285 590 890
40 130 245 500 760
50 115 215 440 670
60 105 195 400 610
The values are based on a specific gravity of 0.60 (typical
for natural gas). See Table 4.3 for capacity correction
factors for gases with other specific gravities.
Table 4.1: Gas Input Rates
Table 4.2: Maximum Capacity of Pipe (CFH) for a
Pressure Drop of 0.3" of Water
Table 4.3: Maximum Capacity Correction Factors
for Specific Gravity other than 0.60
Specific
Gravity
0.50 0.55 0.60 0.65 0.70 0.75
Correction
Factor
1.10 1.04 1.00 0.96 0.93 0.90
Specific
Gravity
0.80 0.85 0.90 1.00 1.10 1.20
Correction
Factor
0.87 0.84 0.82 0.78 0.74 0.71
Specific
Gravity
1.30 1.40 1.50 1.60 1.70 1.80
Correction
Factor
0.68 0.66 0.63 0.61 0.59 0.58