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Model TS420
11
NOTE – Calibrating the TS420 in normal atmospheric air may introduce a considerable error
due to the affects of temperature and humidity. Ambient temperature and humidity can affect
the amount of oxygen in the atmosphere (see Figure 9).
Figure 9 Change in % Oxygen in the atmosphere with Relative Humidity at constant Temperature
4.5 Sensor Replacement Procedure
The following is the procedure to replace a TS420 sensor.
IMPORTANT - Each sensor is shipped in a plastic bottle. DO NOT remove the sensor until you
are ready to apply power to the system. To ensure proper sensor response, each TS420 must
be calibrated in the field upon initial installation.
1. Unscrew the TS420 sensor cap.
2. Pull sensor out of the TS420 using your fingers. The sensor is a plug-in type, and the
sensor will have a snug fit.
NOTE - The TS420 output will drop to 3.5mA when the sensor is removed, indicating a fault
condition.
3. If the new sensor is in a plastic storage container, then remove lid ring and uncap jar.
Remove the sensor from the container. Save the storage container for later use.
Remove paper liner on sensor gasket if present.
19.00
19.50
20.00
20.50
21.00
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Relative Humidity (%)
% Oxygen
0C
20C
40C