High Gas Pressure Test - Watts Aerco Benchmark OMM-0124 Installation And Start-Up Manual

Benchmark 5000-6000 Boiler Installation & Startup Manual
SECTION 5: SAFETY DEVICE TESTING

5.3 HIGH GAS PRESSURE TEST

To simulate a high gas pressure fault perform the following steps:
HIGH Gas Pressure Test Instructions
1. Shut off the external gas supply by closing the external gas supply ball valve.
2. Locate the port on the top of the NATURAL GAS High Gas Pressure Switch (see Figure
5-3) and loosen the screw inside a few turns to open it. Do not remove this screw
completely. Alternatively, you can remove the 1/4 inch plug shown in the top half of Figure
5-3 and install a hose barb fitting in that location.
3. Attach one end of the plastic tubing to the port or barb fitting and the other end to a 0 – 16"
W.C. (0 – 4.0 kPa) manometer.
4. Apply the reading of the manifold pressure taken in Step 15 of section 4.5.1 (Natural Gas
train) and/or 4.5.2 (Propane gas train), and plug them into the following formulas, which
calculate the maximum allowable gas pressure:
•
Natural Gas Pressure → ______ x 1.5 = ______ max gas pressure
•
Propane Gas Pressure → ______ x 1.5 = ______ max gas pressure
5. Remove the cover from the High Gas Pressure switch and set the dial indicator to 20 (the
maximum).
6. Open the external gas supply ball valve upstream of the unit.
7. Start the unit in MANUAL mode and adjust the Air/Fuel Valve position to bring the unit up
to 100%,
8. Slowly increase the manifold gas supply pressure by turning the Gas Pressure Adjustment
Screw in the Downstream SSOV (see Figure 5-2) while reading the CO level on the
combustion analyzer. Adjust the manifold pressure until the CO reading is 300 ppm. Note
the number of turns you make, as you will turn it back to its original position in step 11,
below.
Figure 5-2: SSOV with Gas Pressure Adjustment Screw Location
9. Take a reading of the manifold gas pressure. If the manifold pressure is greater than the
maximum calculated in step 3, then use the Gas Pressure Adjustment Screw to decrease
the manifold pressure until it is at the maximum allowed.
10. Slowly turn the indicator dial on the High Gas Pressure Switch until the unit shuts down
due to a gas pressure fault. This is the setpoint.
11. Readjust the manifold gas supply pressure to what it was before it was increased in step 8.
OMM-0123_E • GF-207 • 12/17/2019 Technical Support • (800) 526-0288 • Mon-Fri, 8 am - 5 pm EST
BRASS HEX HEAD
(Remove to access
the Gas Pressure
Adjustment Screw).
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