Instruction manual

1.0 OVERVIEW SM425 INSTRUCTION MANUAL
1.0 OVERVIEW
The SM425 Separate-type Zircon Oxygen Analyzer is used to monitor and control the oxygen
concentration in combustion gases. Applications include boilers and industrial furnaces in industries
which consume considerable energy such as steel, electric power, oil, petrochemical, ceramics, paper,
pulp, food, textiles, incinerators, and any plant using medium/small boilers. It can help conserve energy in
these industries. The SM425 also contributes to preservation of the earth’s environment in preventing
global warming and air pollution by controlling complete combustion to reduce CO
2
, SOx, and NOx.
The SM425P Separate-type Detector uses a high-reliability Zirconia sensor with a heater assembly that
can be replaced on site. The detector can be mounted on the wall of a flue and measure the gases
directly. The SM425P detector is used in applications where sample gas temperatures range from 0 to
700°C. The SM425 analyzer can be used in combustion gases at temperatures up to 1400°C if equipped
with a general-use 0.15m long detector and a high-temperature probe adapter, ZO21P-H. Refer to
Section 1.2.2 of this manual for detector descriptions and applications.
The converter is equipped with an LCD touch screen display which has various setting displays,
calibration information, and oxygen trending. The converter is equipped with various standard functions
such as measurement and calculation as well as maintenance functions that include self-test. Analyzer
calibration can be fully automated with the SM425CAL, an automatic calibration unit, installed.
Some examples of typical system configurations are illustrated below:
1.1 SM425 System Configuration
The system configuration should be determined by the desired operating conditions; e.g. whether
calibration is to be automated and whether flammable gas is present and requires safety precautions. The
system configuration can be classified into three basic patterns as follows:
1.1.1 System 1
This is the simplest system consisting of a detector and a converter. This system can be implemented for
monitoring oxygen concentration in the combustion gases of a package boiler. No piping is required for
the reference gas (air) which is fed in at the installation site. The portable ZO21S standard gas unit is
used for calibration. Zero gas from this unit and span gas (air) is sent to the detector through piping
connected during calibration.
- As this system uses ambient air for the reference gas, measuring accuracy will be affected by the
installation location.
- A needle (stop) valve should be connected to the calibration gas inlet of the detector. The valve should
be fully closed unless calibration is in progress.
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