Teledyne 7120 - NDIR analyzer - Manual (Page 7)

1-3
Photometric Analyzer Introduction 1
Teledyne Analytical Instruments
1.4 General
A dual channel electro optical infrared analyzer is utilized to continu-
ously monitor either percentage or Part Per Million (PPM) concentrations of
the gas of interest. Measurements are displayed on integral digital display.
The system is insensitive to the thermal, spectral interference, contamination
and zero drift problems normally associated with systems employing IR
photometers.
Sample preparation requirements are absolutely minimal and entail only
cooling and the automatic removal of heavier particles. Drying of the sample
is unnecessary provided no condensation can occur for ambient and sample
temperatures and pressures.. The system is simple, cost effective, and con-
tains no critical orifices, sample blending, or processing that might contribute
to increased maintenance and system downtime.
Additional features include direct reading linear output and an elec-
tronic automatic zero that compensates for analyzer drift over a period of
time.
1.5 NDIR Analyzer
The analyzer is a non-dispersive infrared (NDIR) gas analyzer measur-
ing the concentration of one gas of interest in a multicomponent gas mixture.
The measurement is accomplished by the infrared absorption of the desired
component in the mixture.
Basically, the analyzer consists of an optical unit for gas analysis and an
output Control Unit. The simplicity of construction of the overall analyzer
makes it one of the most advanced in the industry.
The optical unit contains an infrared energy dual element source, an
optical chopper, measurement and reference tubes, optical filter and detector.
The detection circuitry is mounted on its own printed circuit board for
convenient servicing and signal tracing. Test points have been provided at
major points required for adjustment and calibration.
Linearization is accomplished through software providing a linear
output voltage and/or current with the full scale range of the interest gas
concentration. Circuitry necessary to drive the display and to provide volt-
age and/or current outputs for external recorders or indicators is located in
the control Unit. Software timer used, for automatically zeroing the ana-
lyzer, can be programmed on the front panel.