Teledyne API M452 Ozone Sensor Instruction Manual, 02852, Rev. E
5-3
5.4 Invalid Reading
The normal state for the Invalid Reading output is OFF. If this output
turns on, this indicates that the M452 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 M452 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.
5.5 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 600mV.
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 accurate measurement is no longer
possible.