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3.2 Temperature Effects
The MaxO2+ will hold calibration and read correctly within ±3% when at 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:
•
For best results, perform the calibration procedure at a temperature close to the
temperature where analysis will occur.
•
Allow adequate time for the sensor to equilibrate to a new ambient temperature.
CAUTION:
“CAL Err St” may result from a sensor that has not reached thermal equilibrium.
When used in a breathing circuit, place the sensor upstream of the heater.
3.3 Pressure Effects
Readings from the MaxO2+ are proportional to the partial pressure of oxygen. The partial pres-
sure is equal to the concentration times the absolute pressure.
Thus, the readings are proportional to the concentration if the pressure is held constant.
Therefore, the following are recommended:
•
Calibrate the MaxO2+ at the same pressure as the sample gas.
•
If sample gases flow through tubing, use the same apparatus and flow rates when
calibrating as when measuring.
3.4 Humidity Effects
Humidity (non-condensing) has no effect on the performance of the MaxO2+ other than dilut-
ing the gas, as long as there is no condensation. Depending on the humidity, the gas may be
diluted by as much as 4%, which proportionally reduces the oxygen concentration. The device
responds to the actual oxygen concentration rather than the dry concentration. Environments
where condensation may occur are to be avoided since moisture may obstruct passage of
gas to the sensing surface, resulting in erroneous readings and slower response time. For this
reason, the following is recommended:
•
Avoid usage in environments greater than 95% relative humidity.
•
When used in a breathing circuit, place the sensor upstream of the humidifier.
HELPFUL HINT:
Dry sensor by lightly shaking moisture out, or flow a dry gas at two liters per
minute across the sensor membrane.
4.0 CALIBRATION ERRORS AND
ERROR CODES
The MaxO2+ analyzers have a self test feature built into the software to detect faulty calibra-
tions, oxygen sensor failures, and low operating voltage. These are listed below, and include
possible actions to take, if an error code occurs.
E02:
No sensor attached
•
MaxO2+A: Open unit and disconnect and reconnect sensor. Unit should perform an auto
calibration and should read 20.9%. If not, contact Maxtec Customer Service for possible
sensor replacement.
•
MaxO2+AE: Disconnect and reconnect external sensor. Unit should perform an auto
calibration, and should read 20.9%. If not, contact Maxtec Customer Service for possible
sensor replacement or cable replacement.
E03:
No valid calibration data available
•
Make sure unit has reached thermal equilibrium. Press and hold the Calibration Button
for three seconds to manually force a new calibration.
E04:
Battery below minimum operating voltage
•
Replace batteries.
E06:
Non-compatible oxygen sensor, see note below.
•
Replace batteries.
CAL ERR ST:
O2 Sensor reading not stable
•
Wait for displayed oxygen reading to stabilize, when calibrating the device at 100%
oxygen.
•
Wait for unit to reach thermal equilibrium, (Please note that this can take up to one
half hour, if the device is stored in temperatures outside the specified operating
temperature range).
CAL ERR LO:
Sensor voltage too low
•
Press and hold the Calibration Button for three seconds to manually force a new
calibration. If unit repeats this error more than three times, contact Maxtec Customer
Service for possible sensor replacement.
CAL ERR HI:
Sensor voltage too high
•
Press and hold the Calibration Button for three seconds to manually force a new
calibration. If unit repeats this error more than three times, contact Maxtec Customer
Service for possible sensor replacement.
CAL ERR BAT:
Battery voltage too low to recalibrate
•
Replace batteries.
NOTE:
If you receive a E01, E05, or an E07 error code, correct by ensuring the calibration gas is
either room air or 100% oxygen. Also ensure the calibration gas flow, pressure and concentra-
tion is constant. Allow sufficient time for the sensor to stabilize in the calibration gas and with
room temperature, then attempt to calibrate again.
If these steps do not correct the error, contact Maxtec for technical support.
NOTE:
Use only a Maxtec approved Max-550E sensor called out in Section 9.0 of the Spare Parts
List. The Max550E sensor is equipped with an authentication chip to ensure the monitor is used
with an approved sensor.
NOTE:
Correcting E02, E06, or E07 errors:
1. Disconnect the sensor and reconnect, making sure the male plug is fully inserted into
the receptacle before tightening the threaded locking shroud. The analyzer should now
perform a new calibration with the error cleared.
2. If the error still persists, remove the batteries, wait 30 seconds, then reinstall to
perform a factory reset and diagnostic on the analyzer. The analyzer should again
perform a new calibration with the error cleared.
3. Contact Maxtec Customer Service Department if the error code cannot be cleared.
5.0 CHANGING THE BATTERIES
Batteries should be changed by service personnel.
•
Use only brand name batteries.
•
Replace with two AA batteries and insert per orientation marked on the device.
Should the batteries require changing, the device will indicate this in one of two ways:
•
The battery icon on the bottom of the display will begin to flash. This icon will continue
to flash until the batteries are changed. The unit will continue to function normally for
approx. 200 hours.
•
If the device detects a very low battery level, an error code of “E04” will be present on
the display, and the unit will not function until the batteries are changed.
To change the batteries, begin by removing the
three screws from the back of the device.
A #1 Phillips screwdriver is required to
remove these screws.
Once the screws are removed,
gently separate the two halves
of the device.
The batteries can now be replaced from
the back half of the case. Be sure to orient the new
batteries as indicated in the embossed polarity on
the back case.
NOTE:
If the batteries are installed incorrectly the
batteries will not make contact and the device will
not operate.
FIGURE 2