Ammonia Detector - Manual
NH3/ENH3
April.10
Automatikprodukter
Electrochemical Transmitter
Software calibration via PC
In the standard version (equipped with the communication connector X12) calibration can also be done by means of the
configuration and calibration software.
Software calibration is possible for both control modes.
5.2
Manual Calibration
5.2.1 Zero-point
•
Connect the calibration adapter carefully to the sensor element.
•
Apply zero calibration gas, (0,3 l/min; 1 Bar ± 10%), or other clean air source to the sensor element.
•
Wait 3 minutes until the signal is about 40 mV and stable, then press the button Zero for 5 seconds. Finished!
After successful calibration the measuring signal is corrected automatically.
Depending on the selected signal starting point the measuring signal shows the following values:
Signal start at 2 V or 4 mA
40 mV = 0 ppm
Signal start at 0 V or 0 mA
0 mV = 0 ppm
If the zero-point is out of the admissible range (> 20 mV at starting point 0% / > 60 mV at starting point 20%)
before calibration, there is no correction of the measuring signal.
The sensor has to be replaced.
•
Remove calibration adapter carefully by turning lightly. Inspect close seat of sensor element!
5.2.2 Gain
•
Connect calibration adapter carefully to the sensor element.
•
Apply test gas NH
3
(20 to 70 % of the measurement range) to the sensor (0,3 l/min; 1 Bar ± 10%)
•
Wait 3 minutes until the sensor is stable, adjust signal with gain potentiometer ”Gain” until the signal corresponds
to the appropriate mVDC ± 3 mV (see calculation control voltage 5.3) and is stable.
•
Remove calibration adapter with a careful light turn. Inspect the correct mounting of the sensor element.
By limiting the gain factor, calibration will not be possible any more when the sensitivity of the sensor reaches a
residual sensitivity of 30 %.
Then the sensor has to be replaced.
5.2.3 Calculation of Control Voltage
Control voltage (mV) = 160 (mV) x test gas concentration NH
3
(ppm) + 40 (mV)
measuring range NH
3
(ppm)
Example_
Measuring range NH
3
300 ppm
1000 ppm
Test gas concentration NH
3
205 ppm
405 ppm
Control voltage
149 mV
105 mV
160 (mV) x 205 (ppm) + 40 (mV) = 149 mV.
