Home>
Products & Solutions:
Environmental & Analytical Products:
FAQ:
Oxygen Analyzers:
Oxygen Analyzers, General:
Zirconia Oxygen Analyzers, General:
ZR22G/ZR402G Separate Type Zirconia Oxygen Analyzer:
ZR202G Integrated Type Zirconia Oxygen Analyzer:
ZR22G/ZR402G Zirconia High Temperature Humidity Analyzer:
MG8G/MG8E Paramagnetic Oxygen Analyzer:
OX100/OX102 Limiting Current Type Oxygen Analyzer>
ZR202G/ZR202S Integrated Type Zirconia Oxygen Analyzer

ZR202G/ZR202S Integrated Type Zirconia Oxygen Analyzer

ZR202G Integrated Type Zirconia Oxygen Analyzer system configuration

There are 3 system configurations for the ZR202G Integrated Type Zirconia Oxygen Analyzer depending on the calibration method.
There are 2 methods of feeding in reference air:
one is to feed in air around the detector by natural convection and the other is to use instrument air.
The method of using air around the instrument is simple but there is a problem as described below, so instrument air should be used if it is available.

In case of using natural convection :
Measurement may be affected by the humidity in the air that is fed in. A large variation in humidity causes a measurement error, so care is required.

In case of using instrument air :
Air that has been dehumidified at a dew point temperature of −20℃ or less and from which oil mist and dust have been removed should be used.

(1) Example of System 1 (Calibration method: Simple)
The simplest device configuration is used for a package boiler or other applications. Air in the vicinity of the installation location is introduced as a comparison gas.
Calibration is performed manually, and the zero gas and span gas (air) are introduced to the sensor via the ZO21S standard gas unit.
Example of System 1

(2) Example of System 2 (Calibration method: Manual)
This system is for monitoring and controlling oxygen concentration in the combustion gases of a large-size boiler or heating furnace.
Instrument air (clean and dry air of oxygen concentration 21%) is used as the reference gas and the span gas for calibration.
Calibration is performed manually, and the zero gas (in cylinder) and span gas (instrumentation air) are supplied via the ZA8F flow setting unit.
Example of System 2

(3) Example of System 3 (Calibration method: Auto)
This example represents typical applications in large boilers and heating furnaces, where is a need to monitor and control oxygen concentration.
The reference gas and calibration-time span gas are (clean, dry) instrument air.
Calibration is performed by the ZR20H auto-calibration unit in accordance with the instructions from the converter.
Example of System 3

Note:
That the installation temperature limits for integrated unit range from -20 to 55℃.

→ Return to questions

The condition of sample gas?

The following shows the sample gas conditions for measurement with the ZR202G Integrated Type Zirconia Oxygen Analyzer.

•	Sample Gas Temperature：0 to 700℃ (The analyzer cannot be used for gases at a temperature of more than 700℃)
•	Sample Gas Pressure：-5 to 250 kPa (When the pressure in the furnace exceeds 5 kPa, pressure compensation should be specified.)

→ Return to questions

Notes on installation location and installation of sensor

Be aware that when the installation location of the integrated type zirconia oxygen analyzer is not appropriate, the measurement results may be incorrect, and the heater may burn out and the sensor may be damaged within a short time.
Since the notes on installation location and installation of the integrated type zirconia oxygen analyzer are the same as those of the separate type zirconia oxygen analyzer, refer to the Q&A section of the ZR22G and ZR402G Separate Type Zirconia Oxygen Analyzers.

→ Return to questions

Measurement range and output range setting

• Oxygen Concentration : 0.01～100 vol%O₂
• Minimum Output Range : 0～5 vol%O₂
• Maximum Output Range : 0～100 vol%O₂
Any range can be set within the above range in 1 vol%O₂.
A partial range can also be set.

→ Return to questions

What is the output signal?

Two current outputs (4 to 20 mA DC) are available for the ZR202G Zirconia Oxygen Analyzer.
Any output range of measurement (oxygen concentration) can be set in the range from 0 to 5 or from 0 to 100 vol%O₂.
A partial range can also be set (the ratio of the maximum to the minimum is 1.3 or more).
Furthermore, the following output function can be set.

• Smoothing factor setting
When the oxygen concentration in the sample gas changes rapidly and these values are used for control, some problems will occur; for instance, the on and off operation must be performed frequently. In such a case, the changes in the signal can be smoothed by providing a proper time constant.
The time constant can be set in the range from 0 to 225 seconds.

→ Return to questions

Can the output be held during maintenance?

The output signal can be held at the last measured value or at a preset value during the warm-up period, during calibration, and when an error occurs. The following table shows the relationship between the device status and the analog output hold values that can be set.

Output Hold Setting

→ Return to questions

What are the contact inputs?

Up to 2 contact inputs can be connected to the ZR202G Integrated Type Zirconia Oxygen Analyzer. The contact input performs a preset function by receiving a dry (non-voltage) contact signal from the outside.
The following table shows a list of setting items and functions.

Item	Function
Calibration-gas press. low	While the contact signal is on, neither semi-automatic nor automatic calibration is possible.
Measuring range change	While contact input is on, analog output 1 range is switched to 0 to 25%O₂. While range is switched by the contact input, [Range] is displayed on the screen.
Calibration start	If the contact signal is applied, semi-automatic calibration starts (only if the semi-automatic or automatic mode has been setup). Calibration is started with an applied one- to 11-second time interval single-output contact signal. Even if a continuous contact signal is applied, a calibration is not repeated. If you want to perform a second calibration, turn the contact signal off and then back on.
Process upset	If the contact signal is on, heater power will be switched off. Upset (A one- to 11-second time interval single-output signal is available as a contact signal.) If this operation starts, the sensor temperature decreases and an error occurs. To restore it to normal, turn the power off and then back on, or reset the analyzer.

→ Return to questions

What are the contact outputs?

Two contact outputs are available for the ZR202G Integrated Type Zirconia Oxygen Analyzer.
Contact output 1 allows you to select excitation or non-excitation. The setting items can also be selected.
Contact output 2 is set to excitation and linked to the safety switch of the sensor heater power supply. Accordingly, when contact output 2 is output, the power supply of the sensor heater is stopped, and as a result, a cell electromotive force error (Err-01) or a heater temperature error (Err-02) occurs.
The following items can be set.

(1) Alarm and Error settings
　　• High-high-limit alarm
　　• High-limit alarm
　　• Low-limit alarm
　　• Low-low-limit alarm
　　• Error

(2) Other settings
　　• Warm-up
　　• Calibration
　　• Maintenance
　　• Output range change ("answer-back signal to a contact input")
　　• Calibration-gas press. Low ("answer-back signal to the contact input")
　　• Process upset ("answer-back signal to the contact input")

→ Return to questions

How is error diagnosis performed?

The integrated type zirconia oxygen analyzer is able to detect errors and alarms with the self-diagnosis function.

(1) Error
An error is detected if any abnormality is generated in the detector or the converter, e.g., in the cell (sensor) or heater in the detector, or the internal circuits in the converter.
If an error occurs, the converter performs the following:

•	Stops the supply of power to the heater in the detector to insure system safety.
•	Causes an error indication in the display to start blinking to notify of an error generation.
•	Sends an output contact if the error is set up for "Output contact setup" for that contact.
•	Changes the analog output status to the one set in "Output hold setting".

The content of errors that are displayed includes those shown below the table.
Error

(2) Alarm
When an alarm is generated, the alarm indication blinks in the display to notify of the alarm.
If an alarm is generated, such measures as turning off the heater power are not carried out. The alarm is released when the cause for the alarm is eliminated.