Teledyne 7500ZA - page 29

NDIR Gas Analyzer Instalation
Teledyne Analytical Instruments 13
Without O2
Sensor Built-in O2 Sensor External O2 Sensor
measurement. of 90 to 100% on
the measuring
range
90 to 100% on
the measuring
range.
90 to 100% on
the measuring
range.
Span gas for O2
measurement
—
Gas with conc. of
90 to 100% on
the measuring
range or
atmospheric air
(21% O2).
(O2 gas of 95 to
95.5 vol% for
reverse range O2
measurement.)
O2 gas at 1 to 2%
3.4.4 Internal Purging of the Instrument Housing
The internal housing does need not be purged except under the
following conditions:
1. A combustible gas component is contained in the sample gas.
2. Corrosive gas is contained in the atmospheric air at the
installation site.
3. The same gas as the sample gas component is contained in the
atmospheric air at the installation site.
In such cases, the analyzer housing should be purged with the
instrument air or dry N2.
The purge flow rate should be set to about 1L/min. The purge gas
must be free of dust and moisture.
3.4.5 Pressure at Sample Outlet
Pressure at the sample gas outlet should be atmospheric pressure.
Make sure there are no kinks or obstructions in the exhaust line.