3.34
3.10.8.4 Span Gas Flow Failure - 64
Identical to zero gas flow failure (Section 3.10.8.3). The time out period for the DV lag is in
parameter 52 and for the 90% point in parameter 53.
3.10.8.5 Sample Gas Flow Failure - 65
This is only available if the optional sample flow alarm is fitted. It is cleared when sample flow
returns to normal.
3.10.8.6 Gas Limits Exceeded - 66
See Section 3.6.3 for description of this alarm. This is cleared by performing a manual
calibration or by a successful auto-calibration.
3.10.8.7 Oxygen Level Alarms In Auto-Calibration
The oxygen level alarms will be triggered by the change in the oxygen signal as a result of the
calibrating gases passing through the analyser. The user can make use of the auto-calibration
alarm (46) and external logic functions to inhibit any external annunciators.
3.10.10 Electrical Power Failure In Auto-Calibration
Assuming that the battery back-up of memory is good, then should electrical power fail during
the auto-calibration sequence then when the analyser restarts the sequence is aborted and the
previous calibration is still valid. The next auto-calibration will occur at the programmed time
interval after the restoration of power.
If the power interruption occurs during normal operation then the clock which controls the
auto-calibration repetition time is stopped but its settings retained in memory. When electrical
power is restored the clock starts running again but the next auto-calibration will be delayed by
the duration of the power interruption.
If the battery back-up of memory has failed then the complete memory is erased and the
analyser, including auto-calibration functions, will have to be reprogrammed.
3.11 PRESSURE COMPENSATION CALIBRATION PROCEDURE
Pressure compensation is not available with 1100H high temperature systems (1132
Transducer).
It is not essential to know accurately the oxygen content of the gas used for calibrating
pressure compensation. For the calibration sequence the sample gas stream may be used
provided the oxygen content remains constant to within 0.01% oxygen. In the following
description it is assumed that the zero and span calibration have been satisfactorily completed.
There has to be a means of putting a back pressure on the analyser. The most convenient
way to do this is to use the back pressure valve supplied by Servomex. This is designed to be
placed on the bypass of the 1161 sampling system and will give the correct back pressure
when the bypass flow is 4 to 6 litres/min. It will have been provided with the sampling system.
Note: The maximum cell pressure is 4 psig (28 kPa).
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