YOKOGAWA IR400 series, User Manual

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<3. INSTALLATION>
3-7
IM 11G02N01-01E
3.4 Sampling
3.4.1 Conditions of sampling gas
1. Dust contained in the sampling gas should be completely removed with a filter. For the final
stage filter, use a filter that allows removing dust particles of 0.3 mm.
2. Dew point of sampling gas must be lower than the ambient temperature to avoid occurrence of
drain in the gas analyzer. If vapor is contained in the sampling gas, dew point should be lowered
to 0°C by using a dehumidifier.
3. If SO
3
mist is contained in the sampling gas, use a mist filter or cooler to remove SO
3
mist.
Other mists should be removed by using a mist filter or cooler.
4. Corrosive gases such as Cl
2
, F
2
and HCl, if they are contained in the sampling gas in
considerable amounts, will shorten the life of instruments.
5. Temperature of sampling gas should be within 0 to 50°C. Provide a means that prevents entry of
hot gas directly into the instrument.
3.4.2 Sampling gas flow
Flow of sampling gas should be 0.5 ± 0.2 L/min.
Avoid flow fluctuation during measurement.
Observe the flow reading by a flowmeter provided as shown in the example of the sampling system
configuration (Item 3.4.7).
3.4.3 Preparation of standard gas
Routine calibration is required by standard gas for keeping this instrument under normal operation
condition (once a week). Prepare a standard gas cylinder for zero calibration and span calibration.
Analyzer without
O
2
measurement
Analyzer with built-in
O
2
sensor
Analyzer with external
zirconia O
2
sensor
Zero gas N
2
gas N
2
gas Dry air or atmospheric air
Span gas other
than for O
2
measurement
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
Span gas for O
2
measurement
Gas with concentration of
90% or more of full scale or
atmospheric air (21%)
1 to 2%O
2
3.4.4 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.