3.29
3.10.3 Initial Programming
To set up auto-calibration initially the following parameters will need to be adjusted to tune the
analyser to the sampling system and to ensure that failure modes are detected.
Code Function Range Default value
49 Zero to Span DV lag 0-163.00secs 90.00
50 Zero to Span 90% response 0-163.00 secs 90.00
51 Span stabilisation time 0-15.00 mins 5.00
52 Span to Zero DV lag 0-163.00 secs 90.00
53 Span to Zero 90% response 0-163.00 secs 90.00
54 Zero stabilisation time 0-15.00 mins 5.00
55 Zero to Sample DV lag 0-163.00 secs 90.00
56 Zero to Sample 90% response 0-163.00 secs 90.00
57 Return to Sample time 0-15.00 mins 1.50
The default values which have been chosen should provide adequate detection of fault
conditions with most combinations of design of sampling systems and flowrates.
Where the design of sampling system could result in particularly long response times, or
where a high degree of integrity in the operation of auto-calibration is required, then the
values for parameters 49 to 57 may need to be changed.
It is recommended that the analyser is calibrated manually and then a number of
auto-calibrations are performed under different conditions of flow, gas pressures, etc.
The actual response times measured during auto-calibration are stored in parameters 25 to
30. These can be used as a guide to setting parameters 49 to 57.
Code Function Equivalent to Code No.
25 Zero to Span DV lag 49
26 Span stabilisation time 51
27 Span to Zero DV lag 52
28 Zero stabilisation time 54
29 Zero to Sample DV lag 55
30 Sample stabilisation time 57
In setting times for parameters 49 to 57 a balance has to be achieved between detecting faults
and causing false alarms.
For example, the function of parameter 49, the Zero to Span DV lag, is to abort the
auto-calibration if no span gas is flowing. Depending on design of sample system the analyser
should detect a change in oxygen reading within a few seconds of span gas being selected.
Hence this time should be long enough for the gas to flow into the analyser but not so long as
to excessively delay the time before a Span gas flow alarm is raised and the analyser aborts
auto-calibration and returns to reading the sample gas.
To Next Page
Loading...
Need help?
General
