There is only one calibration adjustment necessary for the 9070 oxygen sensor. This is the Sensor Offset. An incorrect
value for the sensor offset will affect an oxygen reading at 21% by about 1% oxygen in every 1 mV of offset, but will
have very little effect on oxygen readings below 2% oxygen.
To remove this error, ensure that the normal volume of gas is passing through the gas sample line (approximately 300
cc/min). In this condition, the zirconia sensor should have no oxygen partial pressure difference across the cell. (Air is
also used as reference gas).
NOTE:
If ‘YES’ has been selected in ‘set-up’ step 10, the offset will be automatically trimmed to keep the Analyzer reading
20.9%.
If ‘NO’ has been selected in ‘set-up’ step 10, the offset can been entered manually in set-up 11, by reading the sensor
‘EMF mV’ from the lower line of the display while in ‘RUN’ mode.
A manual gas calibration check may also be performed if an external 2-way solenoid is connected. This may be
performed simply by pressing the ‘CAL 1’ button on the keyboard. The Analyzer electronics should also be calibrated
according to Section 5.5, Set-up Function Details.
3.15 SENSOR CALIBRATION – CARBON DIOXIDE SENSOR
After power has been applied to the 9070, the carbon dioxide transducer will function almost immediately, however it
is recommended that it is allowed to stabilise for about 15 minutes before making any adjustments.
The calibration of the 9070 carbon dioxide module has two main parts -
Calibration of the ZERO
Calibration of the SPAN
Both parts can be done from the keyboard of the 9070, and the only additional equipment required is a bottle of 100%
carbon dioxide.
Calibrate to ZERO & SPAN once every two months for best performance.
NOTES: -
For best results when calibrating the CO
2
sensor, please observe the following guidelines.
• Don’t connect the test gas directly to the sample pipe of the 9070. Allow the Analyzer to suck the gas in using the
internal pump, as it would in normal use. This can be done by piercing a plastic hose on the outlet of the gas bottle
with the hypodermic needle.
• Piercing the plastic hose with the hypodermic needle and allow the gas to flow for about 30 seconds before
initiating a calibration sequence from the 9070 keyboard.
• If a zero and span calibration is to be carried out, always start with the zero calibration.
• The zero calibration takes longer than the span calibration. The maximum time involved with a zero calibration is
around 50 seconds, and for a span calibration the time is around 40 seconds.
• If a calibration has been unsuccessful due to an interrupted gas flow, contaminated calibration gas, or excessive case
temperature (ie: >50°C (120°F) ), re-initiate the calibration from the 9070 keyboard.
• Do not under any circumstances tamper with or open the CO
2
analysis chamber. Doing so will void the
manufacturers warranty. There are no user serviceable parts inside, and any tampering will drastically reduce it’s
performance and lifetime. Any Analysis chamber sent back for repair which has been tampered with will have to be
replaced.
• If the carbon dioxide module fails, it should be sent back to the manufacturer for repair and factory re-calibration.
CO
2
ZERO CALIBRATION
Leave the sample hypodermic needle open to the air for at least 30 seconds.
Use the function keys to get to set-up mode number 12, “CO
2
Calibrate”.
Teledyne Analytical Instruments 9070 Oxygen Analyzer Page 21
