Teledyne TED-200 - Medical application oxygen monitor - Manual (Page 30)

Appendices
A-4 Teledyne Analytical Instruments
A.5.2 Humidity
Humidity does not directly affect the accuracy of the sensor's measurement.
However, when a nebulizer or other device is used to increase moisture levels in gas
mixtures, the moisture actually dilutes the mixture. This dilution effect decreases the
oxygen concentration.
For example, if an 80% oxygen gas mixture is humidified to saturation at room
temperature, the resulting gas mixture will contain only 77.5% oxygen. Your TED 200-
T oxygen monitor accurately measures decreases in the oxygen concentration due to the
dilution effects of moisture added to gas mixtures.
As with all oxygen sensors, excessive condensation on the sensing surface of the
T-7 will block the diffusion of oxygen to the sensor, rendering it inoperative. We
recommend installing the sensor on the dry side of the breathing circuit at all times.
Water condensate on the exposed cable contacts at the rear of the sensor may
affect the oxygen reading and should be removed by shaking out the condensed water
and allowing the sensor to air dry.
A.5.3 Temperature
The T-7 oxygen sensor adjusts for ambient temperature changes in the range of
0–40°C (32–106°F). Since the thermistor that compensates for these changes is located
in the rear of the sensor assembly, it is important that gas mixtures, flowing over the
front of the sensor, be at room temperature. Reading errors may occur if hot gases from
a heated humidifier are directed past a sensor teed into a breathing circuit.
A small thermal tracking error may be encountered in application areas where
the entire sensor assembly is placed in the gas mixture to be analyzed (e.g., incubators).
No adjustments should be made during this period (about 1 to 2 hours), since this error
will be eliminated when both the thermistor and sensing electrode have had sufficient
time to come to thermal equilibrium.
A.5.4 Discrepancy in Readings
The TED 200-T should never be used as a primary monitoring device. It is
intended to be used as a secondary oxygen monitor, meaning that it is intended to verify
the accuracy of and check the oxygen concentration leaving another oxygen mixing
device or primary life support system (i.e., a blender or anesthesia machine). Whenever
there is a significant difference in the oxygen readings between the primary and second-
ary monitors, the discrepancy must be resolved immediately. The information obtained
from the TED 200-T should never be used to make adjustments to the primary life-
support system, but should only be used as an indication that the primary device may
require service and/or calibration.