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Percent Oxygen Analyzer Introduction 1
Teledyne Analytical Instruments
Introduction
1.1 Description
The Teledyneg Analytical Instruments (TAI) Model 311PC is a por-
table, intrinsically safe percent oxygen analyzer which can be operated
without an external power source and reliably calibrated without the use of
cumbersome, questionable, so-called “certified” calibration gases.
The instrument provides for percent oxygen analysis in the ranges
0–25%, 0–10%, 0–5%, 0–2.5% and 0–1% oxygen.
Sample oxygen is read from an extremely accurate integral meter
(0.5% linearity) whose range of measurement is determined by the position
of the range selector switch. The 0–2.5% range is read on the 0–25% scale
and the 0–1% range is read on the 0–10% scale. The linear 4.5 inch scale
(mirror equipped to eliminate parallax) provides excellent resolution and
accuracy.
Sample gas is introduced and vented via a pair of quick disconnect
fittings that feature integral shutoff valves which automatically close when
the mating male fitting is withdrawn. The fittings are an integral part of the
measuring cell manifold so that internal sample passage volume is at an
absolute minimum. Sample flow control, although not critical (0.1 to 10
liters/min.), must be accomplished with accessory equipment.
1.2 Method of Analysis
The sample oxygen is measured by a unique electrochemical transducer
which functions as a fuel cell; in this instance, the fuel is oxygen. Oxygen
diffusing into the cell reacts chemically to produce an electrical current that
is proportional to the oxygen concentration in the gas phase immediately
adjacent to the transducers sensing surface. The linear signal produced by
the transducer is amplified by a two stage amplifier. The dual stages of
amplification provide enough gain to drive the 0-100 microampere meter
and thermistor controlled network utilized to compensate for the positive
temperature coefficient of the transducer.
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