Teledyne 326, 327 and 328 - Oxygen analyzers User Manual

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2-1

Operational Theory

Model 326/327/328

Teledyne Analytical Instru-
ments

Operational Theory

2.1 Method of Analysis

The analysis is specific for oxygen; i.e., the measuring cell will not

generate an output current unless oxygen is present in the sample gas. Thus,
the instrument has an absolute zero, and no zero gas is required to operate
the analyzer.

The measuring cell has the ability to respond accurately to the presence

of oxygen irrespective of flowrate. TBE recommends using ambient air as a
span gas or, if that is not possible, using a known calibration gas of about
80% of the range of interest value.

The measuring cell (U.S. Pat. #3,429,796) is a solid-state maintenance-

free structure that carries a TBE guarantee for performance and usable life.
The cell consumes oxygen from the gas surrounding it and generates a
proportional microampere current. The low level signal is then amplified by
a solid-state operational amplifier, and the resulting DC signal is suitable for
driving a high impedance recording device, a temperature compensation
circuit for the cell, and an integral 0-100 µA meter. The output signal is
linear over the specified ranges of analysis.

Temperature compensation maintains a cell output accuracy of ±5% from 0
°C to 50 °C (32 °F to 125 °F) or ±2% of scale at any constant temperature
between the above extremes. Accuracy is limited only by the accuracy of the
recording or indicating device used with the analyzer.

2.2 Transduction and Temperature Compensation

The TBE 326 Series Oxygen Analyzers utilize a unique electrochemical

transducer whose features include:

1) Specificity for oxygen.
2) Maintenance-free operation.
3) Long calibration interval and life.