4) Release both the CALIBRATE key and the ↓ key.
The unit will automatically enter the “LOCKED” condition and return to normal operation.
2.2.4 Factors Influencing Calibration
The primary factors influencing the MAXO2 analyzer are temperature, pressure, and humidity.
Effects of Temperature
The MAXO2 analyzer will hold calibration and read correctly within ±3% when in thermal equilibrium within the operating temperature range. The device must be thermally stable when calibrated and allowed to thermally stabilize after experiencing temperature changes before readings are accurate. For these reasons, the following is recommended:
1)Allow adequate time for the sensor to equilibrate to a new ambient temperature.
2)For best results, perform the calibration procedure at a temperature close to the temperature where analysis will occur.
Pressure Effect
Readings from the MAXO2 analyzer are proportional to the partial pressure of oxygen. The partial pressure of Oxygen (PO2) is equal to the percentage of oxygen (%O2) times the absolute pressure (AP) at which the sample enviroment is measured. (PO2=%O2 x AP). Thus the readings are proportional to the concentration if the pressure is held constant. Flow rate of sample gas can affect pressure at the sensor in that back pressure at the sensing point may change. For these reasons, the following is recommended:
1)Calibrate the MAXO2 analyzer at the same pressure as the sample gas.
2)If sample gases flow through tubing, use the same apparatus and flow rates when calibrating as when measuring.
3)The MAXO2 analyzer oxygen sensor has been validated at pressures up to 2 atmospheres absolute. Calibration or operation above this pressure is beyond the intended use.
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