Teledyne 326, 327 and 328 - Oxygen analyzers - Manual (Page 12)

Teledyne Analytical Instruments 1-6
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1.7.4 Temperature Control and Compensation 1.7.4 Temperature Control and Compensation 1.7.4 Temperature Control and Compensation 1.7.4 Temperature Control and Compensation 1.7.4 Temperature Control and Compensation
Inaccuracies caused by varying temperature conditions are inherent in
most methods of analysis employing transducers. To correct for this, a
system composed of a combination of temperature compensation and
control is used in the 326 series.
To protect the Micro-Fuel Cell against damage from low ambient
temperatures and reduce the range required for the compensation circuit,
the analyzer is equipped with a thermostatically controlled heating system
that will not permit the interior of the instrument to drop below 70 °F.
To eliminate the inaccuracies accompanying the positive temperature
coefficient of the Micro-Fuel Cell, a specially selected thermistor and
network of precision resistors is utilized to produce a negative coefficient of
matching characteristics. The variable element (thermistor) in the compen-
sation network is physically located in the same assembly as the Micro-Fuel
Cell, so that both devices are exposed to essentially the same temperature
conditions.
Compensation techniques for high temperature conditions (up to 125
°F), allow the user to disturb the integrity of the analyzer (by opening the
door or front panel) without the equalibration time that would normally
accompany systems employing only high temperature control. In addition,
the life of the Micro-Fuel Cell is extended by not subjecting it to the high
ambient temperature that would be required in an exclusively temperature-
controlled system.
1.7.5 Modular Electronics 1.7.5 Modular Electronics 1.7.5 Modular Electronics 1.7.5 Modular Electronics 1.7.5 Modular Electronics
The electronic components are mounted on a plug-in printed circuit
board, as are the various optional electronic features, for fast, simple repair.
Although circuit failure is unlikely, plug-in capability of the critical elements
of the circuit facilitates instant solution in the event of a semiconductor
failure—providing the customer backs up his instrument with the recom-
mended spare. The faulty circuit board may then be returned to the factory
for repairs. Having an available spare part is usually more economical the
services of highly trained service personnel. The printed circuit assemblies
are preset and adjusted to be instantly interchanged.
1.8 Optional Features
The following optional features are only available at the time the order
is placed.