DATREND Systems venTest, Руководство по эксплуатации

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venTest OPERATORS MANUAL
4.17 Maintenance and Calibration
4.17.1 venTest and FlowSense Sensors
The basic unit and the FlowSense Sensors should be returned annually to Datrend Systems Inc.
or its authorized service center for maintenance and calibration.
4.17.2 Oxygen sensor
The (optional) oxygen sensor will become less sensitive as it is used. Therefore it must be
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calibrated regularly by the user. This calibration will be carried out with 21 % O (normal ambient
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air) and 100 % O (pure oxygen).
The operating life of the sensor basically depends on 2 factors:
1. Ambient temperature in which the sensor is stored and operated.
2. Oxygen concentration to which the sensor is exposed.
The operating life of the sensor is defined as 900000%h by the manufacturer. Whereas the end of
operating life is defined as a drop under 70% of the original output signal.
This definition is based on an ambient temperature of 20°C and an oxygen concentration of 21%
which means that under these circumstances the sensor has an operating life of 5 years.
However, an ambient temperature of 30°C shortens the operating life to 75%, an ambient
temperature of 40°C to 50% of the specification.
The impact of a higher oxygen concentration is even more significant. With a constant supply of
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40% O the operating life drops to 50% of the specification. At 70% O it is only approx. 30% and
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at 100% O it is only 25% of the initial operating life. If measurement is always made at 100% O
and 20°C, the sensor will be consumed after a little more than one year.
The impact of the ambient temperature and the measured oxygen concentration have a
simultaneous effect and influence on the operating life of the sensor.
These effects require a regular calibration of the sensor. As the decrease in sensitivity of the
sensor over the operating life is typically linear you can set up the following table for the calibration
intervals:
Operation/Chapter 4
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