Teledyne 460H - Manual (Page 35)

7.3 Invalid Reading
The normal state for the Invalid Reading output is OFF. If this output turns on, this
indicates that the M460H is still operational, but a system fault or calibration fault exists
that may make the current ozone reading invalid.
The Invalid Reading output is turned on for any of the following conditions:
1. When the measured pressure in the measurement cell exceeds 45 psia.
2. When the measured concentration has exceeded the full-scale concentration
range of the sensor. Check the serial number tag for the full-scale concentration
range.
3. The sensor is indicating an excessive negative reading.
7.4 Lamp Low
The normal state for the Lamp Low output is OFF. If this output turns on, this indicates
that the UV lamp intensity as measured by the reference detector has dropped below
2500mV.
If the Lamp Low output turns ON and the Sensor O.K. output is ON, this indicates that
the lamp intensity is still adequate for measurement, but adjustment should be made
when possible.
If the Lamp Low output turns ON and the Sensor O.K. output is OFF, this indicates a
failure condition and measurement is no longer possible.
7.5 Cell Dirty
The normal state for the Cell Dirty output is OFF. If this output turns on, then the ratio
of the measure detector to the reference detector (at zero) is < 0.5. This value is
calculated when the zero calibration is performed.
When this output is on, it indicates a loss of optical transmission through the windows in
the absorption cell or a calibration fault.
P/N 03662D Teledyne API Model 460H O3 Monitor Operator Manual - Page 35