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4.2.1 Calibration with Bottled Span Gas
??Switch the function switch to “TEST”- position. Instrument will perform an automatic
selftest.
??Press “Cal” using the keyboard pin. The display will show “000” indicating the automatic
zero adjust.
??When the zero adjust is finished, display will show “GCAL”.
??Mount the cal gas adapter on the sensor.
??Connect the span gas bottle with the cal gas adapter as shown on the picture at page 13.
??Open the span gas bottle and adjust the flow rate to 300 to 400 ml/min.
??Press “Cal”. The display will flash “GCAL” until stable reading has been reached. The
instrument will beep and the display will stop flashing.
??Stop the gas flow.
??Press “Cal” once. Press “Cal” again and hold the key down until the display shows the
concentration of the span gas [% LEL]. The indicated number will start at zero and
increase stepwise until 100 % LEL.
??As soon as the span gas % LEL value is reached, release “Cal” and press “Fct”. The
display will show “Stor” indicating that this value has been stored in memory.
Note:
??During calibration the Compur Ex plus checks the sensitivity of the sensor.
If the sensitivity has decreased below a certain level, the display will show an error
message “Err1” after calibration. In order to erase the error message, switch the
instrument “OFF” and back to “ON”. The detector will measure using the new calibration
value. “Err1” is meant as a warning that the sensor soon might need replacement.
If the sensor sensitivity is to low, you will receive an error message “Err2”. In this case the
sensor needs immediate replacement.
4.2.2 Calibration for Gases not Available as Span Gas
If span gas is not commercially available, the preparation of span gas is a very time
consuming and costly procedure. The Compur Ex plus can be calibrated using commercially
available span gases by applying the response factor indicated on the sensor (Methane instead
of Methanol, Butane for all other components).