Azbil AUR355, User Manual

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Chapter 5. Trial Operation and Adjustment
z Pilot turn-down test
WARNING
For equipment that uses the AUR355 to detect both the pilot and the main burner flame, carry
out the pilot turn-down test carefully. If the flame detector is set so that it detects a pilot flame
that is too small to ignite the main burner, this device will not be able to detect a flame failure
in the main burner. In that case, fuel will continue to be supplied, causing a serious explosion
hazard.
Before doing the pilot turn-down test or ignition spark response test, make sure that all
manual fuel valves are closed.
If the pilot turn-down test must be carried out repeatedly, completely stop all combustion
equipment each time the test is finished, and completely discharge unburned gas or fuel oil
that has accumulated in the combustion chamber, ducts, and flues. Otherwise, an explosion
may result.
After completing the pilot turn-down test, turn off the power switch. Restore the original state
of all test jumpers and limit switches and reset the controller settings. If operation begins
without the above steps, damage to the equipment, gas leak, or explosion may result.
CAUTION
The pilot turn-down test should be carried out only by specialists who have knowledge and
skills concerning combustion equipment and combustion safety.
The purpose of this test is to determine the smallest possible pilot flame that will
reliably ignite the main burner. Before and after this test, make sure to measure the
flame voltage and confirm that it is 2.0 V or more.
(1) Turn off the power to the equipment to stop all devices.
(2) Close the main valve (by removing one side of the wiring to the main valve or
by closing the manual cock) to shut off the gas to the main burner. Open the
pilot valve to its normal position.
(3) Turn on the power switch of the equipment. If the start input is on, the ignition
sequence begins after prepurge, as soon as the pilot valve is opened.
(4) After the pilot burner ignites, turn the pilot valve (manual cock) down until
this device extinguishes the flame. Mark the position of the manual cock at the
time when the flame is extinguished. Then, press the RESET switch to reset the
error and restart the equipment. Turn the manual cock back until just before
the previously marked position (so that more gas is output), and check that
combustion continues.
(5) Turn off the power switch, return the main valve to its normal state (open
the manual cock) and then turn on the power switch again. After prepurge,
pilot burner combustion begins, followed by main burner combustion. If
the main burner does not ignite, turn off the power switch of the equipment
immediately. The main burner does not ignite because the pilot flame is too
small, so it must be increased. After increasing the pilot flame, change the
position of the flame detector so that its monitoring angle is slightly away from
the pilot flame monitoring axis.