AMI Analyzer Manual
Maintenance and troubleshooting
27
Maintenance and troubleshooting
Maintenance:
The Watchdog is virtually maintenance free other than for periodic calibration and occasional sensor
replacement.
Periodic Calibration:
The analyzer should be calibrated about once every month to obtain the best accuracy. The sensor typically
declines in sensitivity by about 1% per month, so a monthly calibration is usually satisfactory. Use in a
particularly aggressive environment may degrade the sensor faster: in this case calibrate more often.
You can see the “Span factor”, the internal calibration coefficient for the sensor, by pressing the UP arrow.
As the sensor ages, during each calibration this factor will increase. It will start around 450, and by the time
it reaches 1000 the sensor is dead. By 850 the sensor is getting pretty dubious, and it would be a good idea
to replace it at that point.
Sensor Replacement:
This should be done periodically, rather than as a response to a dead sensor. See the chart below for
recommended sensor replacement.
Sensor
Part
number
Description
Warrantied life
T2
4SEN09-1
Trace oxygen - CO2 background, up to
10ppm H2S
6 months
T4
4SEN18
Trace oxygen - CO2 background, up to
500ppm H2S
6 months
Table 1. AMI trace sensor types
Shorting clip:
The sensor is shipped with a little slip of metal plugged into a tiny socket as a shorting clip. Place the sensor
in the cell block, and then pull out the shorting clip. This minimizes its exposure to air, and helps it to come
down faster.
