INM MTL 130-0175 Rev 4
1
1
INTRODUCTION
NOTE
“Normal” as used to describe the process and instrument throughout this manual and on
instrument data labels, assumes the following conditions: Oxygen concentration in the
sample is within the range of the instrument; Catalyst Temperature is within the appropriate
limits; Oxygen Sensor Temperature is at its correct operational level.
1.1
Applications
This range of analysers is designed to monitor the oxygen content of the products of
combustion of a pre-mixed air/gas mixture.
1.2
General Description
The system comprises an electronic unit and a separate catalytic reactor/oxygen sensor unit.
Both the catalytic reactor and the oxygen sensor operate at elevated temperature.
The air/gas mixture is passed into the heated catalytic chamber where it combusts; the products
of combustion then pass across a zirconia oxygen sensor. The oxygen sensor produces a signal
proportional to the oxygen content of the gas, which is processed by the microprocessor control
unit. The control unit also provides a digital display and a programmable analogue output (typically
4 to 20mA) linear with oxygen concentration; the default setting is 0 to 5%.
The catalytic reactor and the oxygen sensor are heated by separate control circuits also housed
in the control unit. Their temperatures are controlled and monitored by two independent
controllers mounted on the front panel of the instrument. A volt-free, relay contact is provided
which opens when the sensor temperature or the catalyst temperature is in error.
The flow of gas through the catalytic chamber is indicated and controlled by a flow-meter with a
built-in manual control valve.
1.3
Manual symbols
The following methods are used in this manual to alert the user to important information:-
WARNING
Warnings are provided to ensure operator safety and MUST be followed.
CAUTION
A Caution is provided to prevent damage to the instrument.
NOTE
These are used to give general information to ensure correct operation
