Fluke Biomedical VT Mobile - Manual (Page 40)

VT MOBILE
Operators Manual
3-16
Oxygen Sensor
The Analyzer calculates the oxygen percentage as the fraction of the partial pressure of
oxygen relative to the total pressure. Note that changes in the total pressure (i.e. airway
pressure) result in a change in the partial pressure of the measured oxygen even though
the percentage of oxygen is the same. Since the pressure can change much faster than the
response time of the oxygen sensor, a small transient (1 to 2% of full-scale) error can
occur in the oxygen measurement when there is a fast change in the pressure at the
oxygen sensor.
Whenever you make an oxygen measurement, or when you calibrate or zero the oxygen
sensor, make sure there is sufficient gas flow past the oxygen sensor. The Analyzer needs
only a small flow of gas (e.g., 10 lpm) to ensure that the oxygen concentration at the
oxygen sensor is measured accurately. A small amount of flow must be present to ensure
gas mixing.
Verifying Oxygen Sensor Calibration
Verify the oxygen sensor calibration at the beginning of any day during which you expect
to measure oxygen concentrations. Note that you must calibrate the Oxygen Sensor
before initial verification; the sensor is not calibrated as shipped. The Oxygen Sensor
requires subsequent weekly recalibration at a minimum.
Use the following verification procedure:
1. Connect the Oxygen Sensor as shown in Figure 3-4.
2. Introduce a 10 lpm or greater flow of 100% oxygen through the Oxygen Sensor “T”.
3. Press P to access the O2 display.
4. Ensure that the O2 screen oxygen concentration is 100 % ± 2 % of full scale. If the
concentration is less than 98 %, perform the oxygen sensor calibration as described
below.
5. Replace the oxygen sensor after one year (or longer if no replacement message
appears during calibration.)
Note
The Oxygen Sensor is not calibrated at the factory.
Calibrating the Oxygen Sensor
Calibrating the Oxygen Sensor improves pressure compensation for barometric and
airway pressure changes. Figure 3-4 portrays Oxygen Sensor connections.