| Q1 |
Separate type zirconia oxygen analyzer system configuration |
| A1 |
The system configuration of zirconia oxygen analyzers is divided into two main types, those using either a general-use detector (measurement gas temperature of 700℃ and below) or those using
a high-temperature detector (measurement gas temperature of 1400℃ and below).
Moreover, each of these types is further divided into three subtypes, giving six types in total.
System Block Diagram Types
There are two methods of feeding in reference air : one is to feed in air near the detector by natural convection and the other is to use instrument air.
The method of using air near 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) Type : L1 (simple measurement type)
This is the simplest system configuration and is used for a package boiler, etc.
For the reference air, air near the installation site is fed in. Calibration is done manually and zero
gas and span gas (air) are introduced to the detector via the ZO21S standard gas unit.
System configuration diagram for type L1
(2) Type : L2 (without automatic calibration)
This system is for controlling and measuring oxygen concentration with high accuracy in a large
boiler or heating furnace.
The reference gas uses instrument air. Calibration is done manually, and zero gas (from a
cylinder) and span gas (instrument air) are fed via the ZA8F flow setting unit.
System configuration diagram for type L2
(3) Type : L3 (with automatic calibration)
This system is for controlling and measuring oxygen concentration with high accuracy in a large boiler or heating furnace.
The reference gas uses instrument air. Calibration is performed by operating the automatic calibration unit based on commands from the converter.
System configuration diagram for type L3
(4) Type : H1 (simple measurement type)
This is the simplest system configuration for high-temperature applications and is used for a package boiler, etc.
For the reference air, air near the installation site is fed in. Calibration is done manually and zero gas and span gas (air) are introduced to the detector via the ZO21S standard gas unit.
System configuration diagram for type H1
(5) Type : H2 (without automatic calibration)
This system is for controlling and measuring oxygen concentration with high accuracy in a large boiler or heating furnace.
The reference gas uses instrument air. Calibration is done manually, and zero gas (from a cylinder) and span gas (instrument air) are fed via the ZA8F flow setting unit.
System configuration diagram for type H2
(6) Type: H3 (with automatic calibration)
This system is for controlling and measuring oxygen concentration with high accuracy in a large boiler or heating furnace.
The reference gas uses instrument air. Calibration is performed by operating the automatic calibration unit based on commands from the converter.
System configuration diagram for type H3
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| Q2 |
The condition of sample gas? |
| A2 |
| Sample Gas Temperature : |
0 to 1400℃
(If gas with temperatures higher than 700℃ needs to be measured, the high-temperature probe adapter can be used to measure gas of up to 1400℃.) |
| Sample Gas Pressure : |
-5 to 250 kPa |
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| Q3 |
Notes on installation location and installation of sensor |
| A3 |
Be aware that when the installation location of the sensor 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.
Install the sensor in a location that meets the following conditions.
• Easy access for inspection and maintenance.
• Ambient temperature does not exceed 150℃,
and the terminal box is not exposed to radiant heat.
• A clean environment free from corrosive gases.
• Minimum vibration.
Typical good/bad installation examples are shown below for your reference.
Instructions for installation
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| Q4 |
Measurement range and output range setting |
| A4 |
• Oxygen Concentration : 0.01 to 100 vol %O2
• Minimum output range : 0 to 5 vol %O2
• Maximum output range : 0 to 100 vol %O2
Any range can be set within the above range in vol%O2.
A partial range can also be set.
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| Q5 |
What is the output signal? |
| A5 |
Two current outputs (4 to 20 mA DC) are available for the ZR402G Zirconia Oxygen Analyzer Converter.
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.
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| Q6 |
Can the output be held during maintenance? |
| A6 |
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. However, output 1 and output 2 cannot be set separately. The following table shows the relationship between the device status and the analog output hold values that can be set.
Output Hold Setting
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| Q7 |
What are the contact inputs? |
| A7 |
Up to 2 contact inputs can be connected to the ZR402G Zirconia Oxygen Analyzer Converter.
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.
Contact input 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. |
| Blow back start |
The contact signal is on, blow-back starts. (A one- to 11-second time interval single-output signal is available as a contact signal.)
Even if a continuous contact signal is applied, calibration is not repeated. If you want to make a second calibration, turn the contact signal off and then back on. |
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| Q8 |
What are the contact outputs? |
| A8 |
4 contact outputs are available for the ZR402G Zirconia Oxygen Analyzer Converter.
Contact outputs 1 to 3 allow you to select excitation or non-excitation. The setting items also can be selected. The following table shows a list of setting items. Contact output 4 is for excitation and the setting item is fixed to Error.
Contact Output Setting Items
Alarm and Error settings
| Item |
Description |
| High-high-limit alarm |
If "high-high alarm ON" is selected, contact output occurs when the high-high-limit alarm is issued. To do this, it is required, in alarm setup, that the high-high alarm be set on beforehand. |
| High-limit alarm |
If "high alarm ON" is selected, contact output occurs when the high-limit alarm is issued. To do this, it is required, in alarm setup, that the high-limit alarm be set on beforehand. |
| Low-limit alarm |
If "low alarm ON" is selected, contact output occurs when the low-limit alarm is provided. To do this, it is required, in alarm setup, that the low-limit alarm be set on beforehand. |
| Low-low-limit alarm |
If "low-low alarm ON" is selected, contact is on when the low-low-limit alarm is issued. To do this, it is required, in alarm setup, that the low-low |
| Calibration coefficient alarm |
If calibration coefficient alarm is ON (enabled), then when a zero- calibration coefficient alarm (alarm 6) or span calibration coefficient alarm (alarm 7) occurs then calibration coefficient alarm contact output occurs. |
Startup power stabilization
timeout alarm |
If set ON then contact output occurs when startup power stabilization timeout alarm (alarm 8) occurs alarm be set on beforehand . |
| Error |
If "Error ON" is selected, contact output occurs when an error results. |
Other settings
| Item |
Description |
| Warm-up |
If "Warm-up ON" is selected, contact output occurs during warm-up. |
| Warm-up change |
If "Range Change ON" is selected, contact output occurs ("answer-back signal to a range change signal") while a range change signal is applied to a contact input. To do this, it is required, in input contact setup, that the range change be selected beforehand. For more on this. |
| Calibration |
If "Calibration ON" is selected, contact output occurs during calibration. |
| Maintenance |
If "Maintenance ON" is selected, contact output occurs during maintenance. |
| Blow back |
If "Blow back ON" is selected, contact output occurs during blow back. |
| Calibration-gas press. low |
If "Cal. gas press. low ON" is selected, contact output occurs ("answer-back signal to a calibration-gas low-pressure signal")when a calibration-gas low pressure signal is applied to the contact input. To do this, it is required, in input contact setup, that "Cal. gas press. Low" be selected beforehand. For more on this. |
| Process upset |
If "Process upset" is selected, contact output occurs ("answer-back signal to a process upset signal) when the process upset signal is applied to the contact input. To do this, it is required, in input contact setup, that "process upset" be selected beforehand. |
Note :
To provide an alarm with an output contact, be sure to make an alarm setting. When using contact output as an answer-back signal for an input contact, be sure to make an input contact.
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| Q9 |
How is error diagnosis performed? |
| A9 |
The ZR402G Zirconia Oxygen Analyzer is able to detect errors and alarms with its 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" |
When the display shown in below figure appears , pressing the error indication brings up a description of the 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.
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| Q10 |
Replacing existing models |
| A10 |
When you want to leave the existing ZA8C converter as is and only replace the existing sensor with a ZR22G, follow the procedure below.
| • |
When leaving the existing ZA8C converter as is and only replacing the existing sensor with a ZR22G :
The ROM must be replaced and a cold junction temperature compensation board must be installed.
It is recommended that this work be performed by a Yokogawa's service technician.
Part number of ROM: K9290KF (when you use English)
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| • |
When leaving the existing ZA8C converter as is and only replacing the existing sensor with a ZR22G :
The ROM must be replaced and a cold junction temperature compensation board must be installed.
It is recommended that this work be performed by a Yokogawa's service technician.
Part number of ROM: K9290KF (when you use English)
Part number of cold junction temperature compensation board: K9471JA
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| • |
When leaving the existing ZO21D sensor as is and only replacing the existing converter with a ZR402G :
The converter can be connected directly because it is compatible with the existing model. |
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