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6. Check all gas piping for leaks prior to placing the
boiler in operation. Use an approved gas detector,
non-corrosive leak detection fluid, or other leak
detection method. If leaks are found, turn off gas flow
and repair as necessary.
WARNING
When checking for leaks, do not use matches,
candles, open flames or other methods that provide
an ignition source. This may ignite a gas leak
resulting in a fire or explosion.
7. Figure 5.1 shows the gas shutoff valve for the boiler.
This valve is to be used in addition to the gas service
valve shown upstream of the sediment trap.
Figure 5.1: Gas Supply Pipe and Shut-off
D. GAS SUPPLY PIPING - OPERATION
1. The gas line must be properly purged of air to allow
the boiler to operate properly. Failure to do so may
result in burner ignition problems.
2. Table 5.3 shows the maximum and minimum fuel gas
supply pressure to be measured at the gas valve inlet
pressure tap. This pressure tap is depicted in Figure 5.2.
a. Gas pressure below 3.5 inches of water may result
in burner ignition problems.
b. Gas pressure above 13.5 inches of water may
result in damage to the automatic gas valve.
CAUTION
Do not subject the gas valve to more that 1/2 psi (13.5"
W.C.) of pressure. Doing so may damage the gas valve.
Table 5.3: Maximum and Minimum Fuel Pressure
Fuel Type
Minimum
Natural Gas
LP Gas
Pressure Inches W.C. (Pa)
Maximum
3.5
13.5
3.5
13.5
3. To check the gas supply pressure to on the gas valve:
a. Turn off the power at the service switch.
b. Close the gas shutoff valve.
c. Using a flat screwdriver, turn the screw inside the inlet
tap fitting (see Figure 5.2) one turn counter clockwise.
d. Attach the tube from the manometer to the
pressure tap fitting.
e. Open the gas valve and start the boiler.
f. Read and record the gas pressure while the boiler
is firing.
g. Turn off the boiler and close the gas shutoff valve.
h. Remove the manometer tube from the pressure
tap fitting.
i. Turn the internal screw clockwise to close the valve.
j. Turn on the gas shutoff valve and boiler service
switch.
k. Fire the boiler and check for fuel gas odor around
the gas valve. If an odor is evident check to make
sure that the pressure tap fitting is closed.
4. All gas piping must be leak tested prior to placing the
boiler in operation.
a. If the leak test pressure requirement is higher than
13.5 inches of water column, the boiler must be
isolated from the gas supply piping system.
b. If the gas valve is exposed to pressure exceeding
13.5 inches of water column, the gas valve must
be replaced.
5. Install the boiler such that the gas ignition system
components are protected from water (dripping,
spraying, rain, etc.) during operation and service
(pump replacement, condensate collector and
neutralizer cleanout, control replacement etc.)
E. MAIN GAS VALVE - OPERATION
1. Figure 5.2 is an illustration of the gas valve/venturi
assembly for the PureFire boiler.
a. Adjustments should not be made to the gas valve
without instrumentation to measure carbon
dioxide (CO
) and carbon monoxide (CO)
2
emissions in the vent pipe.
Figure 5.2: Gas Valve/Venturi
FUEL PIPING
25
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