Azbil AUR450C - Pilot Turndown Test Procedure

4-3
Chapter 4. TRIALRUN ADJUSTMENT
 Pilot turndown test
This test is intended to check that the flame is reliably transferred to the main
burner when the AUD300C/500C detects a pilot flame if the gas pressure and air
pressure change to their worst conditions.
WARNING
Carry out the pilot turndown 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 the pilot turndown test or ignition spark response test, make sure that all manual fuel
valves are closed.
If the pilot turndown test must be carried out repeatedly, completely shut down all equipment
each time the test is finished, and completely discharge unburned gas or fuel that has
accumulated in the ducts and combustion chamber. Failure to discharge unburned gas or fuel
may result in an explosion.
When the pilot turndown test is complete, turn OFF the power switch to shut down the power.
Restore all test jumpers and limit interlock/regulator settings to their previous states.
If operation begins without the above steps, damage to the equipment, gas leak or explosion
may result.
CAUTION
Only an experienced technician who has knowledge and technical skills related to combustion
equipment and combustion safety should carry out the pilot turndown test.
Handling Precautions
•
If a fuel pressure limit switch is used, and its contacts are open, turn it ON with
a jumper cable during this test.
To carry out the pilot turndown test, follow the steps below.
z Preparations for the test
(1) Turn OFF the power switch.
(2) Close the manual valves to stop the gas supply to the pilot burner and main
burner.
(3) Open the manual valve for the pilot burner.
z Check a gas pressure level at which the Model AUD300C/500C cannot detect the pilot flame
(4) Turn ON the power switch and press and hold the start switch.
>> The ignition operation begins, the pilot valve opens, and the ignition trans-
former is activated. The flame relay turns ON and the FLAME LED lights
up.