36 • T2A Transmitter
NOTE:
Some detected gases use surrogate gases for calibration. Detected gases needing a
surrogate gas for calibration are listed below. If you are using a surrogate gas for
calibration, that surrogate gas concentration multiplied by the factor listed below
should equal about 50% of the detected gas’ full scale.
Zeroing the Sensor (20.9% for O
2
)
The first step of calibration is zeroing (20.9% for O
2
). The zeroing (20.9% for O
2
) process
MUST be performed in known clean air, with no contaminants or hazardous gasses present. If
air quality cannot be guaranteed, a cylinder of zero air will be required to properly zero the
sensor.
1. While the product is in normal operating mode, press the MENU button to activate the
Operation Settings menu.
2. Press the ADD button to begin the zero process and advance to the clean air confirmation
screen.
3. If the sensor is in clean air, press the ADD button to select “Yes” and continue to Step 5.
4. If the sensor is not in clear air:
a. Unscrew and remove the rain guard from the assembly.
b. Install the calibration cup to the T2A’s sensor housing.
c. Screw the regulator into the zero air calibration cylinder.
d. Use the sample tubing to connect the regulator to the calibration cup.
e. Turn the regulator knob counterclockwise to open the regulator.
Table 2: Surrogate Calibration Gases
Detected Gas
Surrogate
Calibration Gas
Factor
ClO
2
Cl
2
1
HF
Cl
2
5
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