Yokogawa IR200 User Manual
Page 17
3 - 4
IM 11G02M01-01E
(
2) Sampling gas flow rate
A flow rate of sampling gas must be 1
±
0.5L/min. A flow meter should be provided as shown in
Fig. 3-2 to measure flow rate values.
(3) Preparation for standard gas
Prepare the standard gas for zero/span calibration.
Zero gas
Without O
2
Analyzer
Built in O
2
Analyzer
Externally mounted
zirconia O
2
Analyzer
N
2
gas
N
2
gas
Dry air, air or gas in
concentration of 80% or higher
of the O
2
range (CO
2
should not
be contained in zero gas if CO
2
meter is provided.)
Span gas except for O
2
Gas with concentration
of 90% or more of full
scale
Gas with concentration
of 90% or more of full
scale
Gas with concentration
of 90% or more of full
scale or atmospheric air
(21%)
Gas with concentration of 90%
or more of full scale
Span gas for O
2
1 to 2% O
2
gas
* We recommend you to feed the zero gas shown above by humidifying it, if NO or SO
2
is included in
components to be analyzed.
(Note)
It is understood to influence the calibration model of the infrared gas analyzer when a lot of H
2
,
He, and Ar are included in the measurment gas (pressure broadening).
The span gas must use a gas near the composition of the measurement gas when you measure the
gas like the above-mentioned.
(4) Reduction of moisture interference
NO and SO
2
measurement is subject to moisture interference.
As shown by the configuration example on the next page, provide a device for humidifying zero
calibration gas, thus controlling the moisture content at a constant level (moisture content in
sample gas should also be controlled here) in configuring a sampling system. That allows the
same moisture content as in the case of measurement to be contained in zero gas for calibration.
(5) Purging of instrument inside
The inside of instrument need not be purged generally except for the following cases.
1.
A combustible gas component is contained in 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 installa-
tion site.
In such cases as above, the inside of analyzer should be purged with the air for instrumentation
or N
2
. Purging flow rate should be about 1L/min.
If dust or mist is contained in purging gas, it should be eliminated completely in advance.
(6) Pressure at sampling gas outlet
Pressure at the sampling gas outlet should be set to atmospheric pressure.