Teledyne 9060 - Zirconium oxide flue gas oxygen analyzer - Manual (Page 64)

9060-Zirconia Analyser
Enter the correct value of ‘M’ (Refer notes in Appendix 1).
52. Purge / Cal Time
Set the first purge to occur at the correct time-of-day. If purging is not required but on-line
auto gas calibration check is required, enter a time-of-day value suitable for the auto
calibration checks. Cal Gas 1 will be tested ten minutes after the purge/cal time and Cal
Gas 2, 20 minutes after. If neither purge nor auto calibration check is required, ignore this
time setting.
Range: 0 to 23 hours in one hour steps. The default time is 12 noon.
53. Automatic Purge
For some oil and coal fired plant, probe filters are necessary and should be back-purged
with sufficient frequency to avoid blocked filters. The outputs will be frozen during purging.
If no purge is required, set-up steps 54, 55 and 56 will be skipped.
Options:
None *
Purge
Auto Offset
++
Key Auto Offset ++
++ Note: If ‘Calibrate’ is selected in set-up step 92 these two additional options will be
available.
If Auto Offset is selected, set-up steps 54 to 56 will be available. By using these steps the
transmitter can be configured to make small corrections to the probe offset automatically.
The offset correction is limited to +/- 3mV.
If Auto Offset is selected set-up 54 and 55 allow the automatic time periods to be set.
If Key Auto Offset is selected the offset correction can be started from the keypad
(PURGE).
54. Time Between Purges
Set the time between purges eg. a two hourly purge or a 100 hourly purge.
Range:
1 to 199 hours. Default setting is 24 hours.
55. Purge Duration
Set up purge duration to a number between three and ten seconds. The filter is actually
purged in less than one second, but three seconds are required for the purge flow switch
to check that the filter is not blocked.
Range:
0 to 10 seconds. Default setting is 10 seconds.
56. Purge Freeze Time
After the purge period the transmitter output will remain fixed (frozen) for an adjustable
period to allow the probe reading to return to the correct process level and avoid output
‘bumps’. The freeze period time required will depend on the probe response time and
thus its design, and whether it has a filter or not.
To determine the required freeze time, manually perform a purge while the plant is in
operation and note the time required for the reading to return to the correct process level
within approximately 0.5 % oxygen.
Range:
10 to 1000 seconds in ten second steps. Default setting is 60 seconds.