Teledyne TED-200 - Medical application oxygen monitor - Manual (Page 29)

Appendices
A-3 Teledyne Analytical Instruments
A.4 Repair Service
PLEASE READ CAREFULLY
In the event that your TED 200-T Portable Oxygen Monitor needs servicing, the
following steps will help to ensure that the repair request is processed promptly.
Contact your authorized TET Sensor Technologies distributor or factory for
return instructions. Do not ship your monitor without first obtaining authorization.
Include a copy of the sales invoice or other proof of purchase date. Warranty
service may be denied if no proof of purchase is included.
It is your responsibility to pay shipping charges to Teledyne Electronic Technolo-
gies. If the unit is under warranty, the serviced or replaced monitor will be returned to
you postage prepaid.
NOTE: Either the TED 200T Oxygen Monitor and/or the T-7 Oxygen Sensor
can be shipped using normal air and ground transportation. No special
environmental conditions for transport and or storage are required.
Monitors and sensors damaged by accident or misuse are not covered by the
warranty. In these situations, service charges will based on time and materials.
A.5 Environmnetal Effects
A.5.1 Pressure
Virtually all gas sensors and monitors measure the partial pressure, not the
percentage, of the gas that they sense. The only time that these instruments can accu-
rately read percentages is when the total pressure does not vary over time between
calibration and use. This is why it is important to calibrate the TED 200-T oxygen
sensor at regular intervals. It is recommended that the unit be calibrated prior to
each use or every 8 hours.
When the sensor is connected to a ventilator circuit, the alternating "breathing"
pressure cycles generated by the ventilator will be sensed as an increase in the oxygen
percentage (especially if the sensor is fast enough to sense the changes, as is the T-7). In
reality, the percentage of oxygen in not changing; it is the total pressure that is increas-
ing, producing a corresponding increase in the partial pressure of oxygen. A hundred-
centimeter water pressure pulse will produce a .11 atmosphere, or an 11% increase in
the total and therefore partial pressure of oxygen. Assuming that the sensor is fast
enough to track this pressure pulse, an unpressurized reading of 50% oxygen will
increase to 55.3% if
the sensor is subjected to a pressure cycle of 100 cm H
2
O. The
reading will rise proportionally less for smaller pressures.