5 Error Checking and Self-Diagnostics
12.04.2016 Mk8 EGA Set-Up and Trim Guide Page 63
5.3.1 Trim Delay
On burner start-up without calibration the EGA performs a drain and starts sampling at 20.9% O
2
(fresh air), which then reduces to the commissioned value. Enough time must be given before the EGA
commences trim, to ensure that it is not correcting the air damper at high O2 values. The total time
delay before the EGA starts to trim is based on the boiler’s residence time. If the total time delay
before trim starts it too short, then a scenario could arise where the EGA reads 5%O2 and over-trims
on air damper, reducing the O2 too far.
If calibration on start-up is active, option 32 (trim delay) must be greater than the calibration time
(parameter 24). A minimum of 40 seconds should be added. Parameter 24 is set as default to 120
seconds, so option 32 should be set to a minimum time of 160 seconds. The total time before trim is
applied is 200 seconds (option 32 + parameter 8); this will also depend on the boilers residence time.
5.3.2 Assembly of Dry Filter
If pump faults are occurring on the EGA it is advised to check the dry filter in the EGA and check for
any blockages and make sure that the filter material has not become saturated.
This filter is specifically used as a dry filter to remove and dust particulate before the dry gas passed
into the cells. The filter is carefully packed as a complete replacement part and should be repacked or
the filter material changed in the field, as the filter is critically calibrated for a specific pressure drop.
The filter should always be dry, if any carryover of liquid or moisture is sent in the filter, please isolate
the EGA and contact Autoflame Technical Support.
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