Gas Piping - PEERLESS GM Installation, Operation & Maintenance Manual

GAS PIPING

5. GAS PIPING
1. Size and install the gas supply piping to provide a
supply of gas sufficient to meet the maximum
demand of all appliances without undue loss of
pressure between the meter and the boiler.
Maximum permissible gas supply pressure to the
boiler is 13.5 inches (3.4 kPa) water column.
2. Determine the volume of gas to be provided to the
boiler. Obtain this value by dividing the Btu per hour
(Watts) rating (on the boiler rating plate) by the
heating value of the gas in Btu per cubic feet (Joules
per cubic meter). Obtain the heating value of the gas
from the gas supplier. As an alternative, use Table
5.1 to obtain the volume of gas to be provided to
the boiler.
Table 5.1: Input
Natural Gas
(Cubic Feet
Model
Per Hour)
GM-05 228
GM-06 285
GM-07 342
GM-08 399
Natural gas based on 1000 Btu/Cubic Foot (37,300 kJ/m³).
LP gas based on 2,500 Btu/Cubic Foot (93,145 kJ/m³).
3. Table 2 shows the maximum flow capacity of several
pipe sizes based on 0.3" w.c. (.08 kPa) of water
pressure drop. These values are based on a specific
gravity of 0.60. Apply the factors indicated in Table 3
for gas with specific gravity other than 0.60 to obtain
corrected capacities.
Table 5.2: Capacity of Schedule 40 Pipe
Capacity of Schedule 40 pipe [cu. ft. per hour (cu. m per
hour)] with pressure drop of 0.3 in. (75 Pa) and specific gravity
of 0.60. No allowance for an ordinary number of fittings is
required.
"
3/4
Pipe
Pipe
Length
Feet
ft.³ m³
10 278 7.8
20 190 5.4
30 152 4.3
40 130 3.7
50 115 3.3
60 105 3.0
Table 5.3: Maximum Capacity Correction Factors
Specific Gravity other than 0.60
Specific Gravity 0.50
Correction Factor 1.10
Specific Gravity 0.80
Correction Factor 0.87
Specific Gravity 1.30
Correction Factor 0.68
14
LP Gas
(Cubic Meter (Cubic Feet (Cubic Meter
Per Hour) Per Hour) Per Hour)
6.5 91 2.6
8.1 114 3.2
9.7 137 3.9
11.3 160 4.5
" "
1 1-1/4
1-1/2
Pipe Pipe
Pipe
ft.³ m³ ft.³ m³ ft.³
520 15 1,050 30 1,600
350 9.9 730 21 1,100
285 8.1 590 17 890
245 6.9 500 14 760
215 6.1 440 12 670
195 5.5 400 11 610
0.55 0.60 0.65 0.70
1.04 1.00 0.96 0.93
0.85 0.90 1.00 1.10
0.84 0.82 0.78 0.74
1.40 1.50 1.60 1.70
0.66 0.63 0.61 0.59
4. Connection of boiler to the gas piping system may
be made on the left side or top of the boiler. See
Figure 11.1 for jacket opening locations.
Use a pipe joint sealing compound that is resistant to
the action of liquefied petroleum gas. A non-resistant
compound may lose sealing ability in the presence of
this gas, resulting in a gas leak and fire or explosion
potential.
5. Install a sediment trap. See Figure 5.1. Locate a tee
in the drop pipe at same elevation as the gas inlet
connection to the boiler. Extend the drop pipe to a
pipe cap. As an alternate, the sediment trap may be
located in the boiler vestibule. See Figure 5.2.
6. Install a ground joint union ahead of the gas control
assembly to permit servicing of the control. Some
local codes require an additional equipment shutoff
valve when using the combination gas controls. If
your code requires such a valve, a suggested
location is shown in Figure 5.1 or 5.2.
7. Check piping for leaks. Use an approved gas
detector, a non-corrosive leak detection fluid or other
leak detection method. If leaks are found, turn off all
gas flow and repair as necessary.
When checking for leaks, do not use matches,
candles, open flames or other methods that provide a
source of ignition. This can ignite a gas leak,
resulting in fire or explosion.
"
m³
45
31
25
22
19
17
0.75
0.90
1.20
0.71
1.80
0.58
Figure 5.1: Gas Connection to Boiler - External
WARNING
WARNING