Step by Step Troubleshooting Procedure for of 02 Analyzer : Paramagnetic Type
A paramagnetic oxygen analyzer detects oxygen concentration using magnetic fields. Various errors can occur, including sensor, sampling system, chamber, calibration, and display issues, each with specific troubleshooting steps to resolve them effectively
O2 Sensor Unit Error
Sensor unit error occurs when sensor electromotive force (emf) is outside specified range as per the manufacturer (for example should be with in -50 mV to 400 mV range)
Possible Causes
Troubleshooting Steps
Drop in auxiliary gas pressure
Check auxiliary gas pressure to ensure it meets specifications with the instrument data sheet.
Excessive flow rate of the sample gas
Verify sample gas flow rate to ensure it is within specified limits as per the manufacturer guidelines
Sensor faulty or not working properly
Verify functionality of thermistors by checking resistance at different temperatures.Inspect electronic sensing circuit for damage or malfunctions.Ensure auto-zero function is working correctly.Check for external magnetic interference.
Problem with Oxygen Sampling System
Possible Causes
Troubleshooting Steps
Sampling System Check
Verify proper gas flow rates and pressures within specified ranges.Ensure filters are clean and moisture removal systems are functional.Perform routine maintenance checks.
Low sample flow readings in Sampling System
Investigate gas sampling integrity, checking for leaks or blockages.Ensure gas sampled accurately represents the environment.
Constant Temperature Chamber Errors
Constant temperature chamber error occurs when the temperature deviates from the manufacturer specified range (Example: 60°C).
Also Constant temperature chamber error occurs during the warmup period.
Possible Causes
Troubleshooting Steps
Fluctuations in power supply voltage.
Restart the analyzer by turning off and on the power. Check constant temperature chamber temperature stability during stabilization period.
Ambient temperature outside the specified range (-5 to 55 °C).
Investigate power supply voltage stability. Ensure ambient temperature falls within specified range.
Heater disconnection or internal thermostat activation
Turn off and on the power. Wait for the constant temperature chamber to cool down. Restart instrument. If error persists, contact Service.
Failure in parts for heater power control system
Investigate heater connection and internal thermostat actionCheck heater power control components . If a still error occurs, verify internal thermostat activation at specified range (70°C.)
Analog Signal Errors
An analog error occurs when there is a failure in the analog circuit
Possible Causes
Troubleshooting Steps
Failure in the analog circuit
Turn off the power and restart the AnalyzerIf error persists, replace the analog card and contact the service center for assistance.
Memory Error
A memory error occurs if there is a failure in reading or writing the memory device.
Possible Causes
Troubleshooting Steps
Failure in reading or writing the memory device.
Turn off the power and restart the analyzer. If error persists, replace the memory with a similar type and contact the service center for assistance.
Calibration Coefficient Errors
Calibration coefficient error occurs when the obtained calibration coefficient is outside the normal range.
Possible Causes
Troubleshooting Steps
Calibration gas concentration mismatch.
Identify and rectify calibration gas concentration discrepancies
Low pressure of auxiliary gas
Ensure auxiliary gas pressure meets specifications
Absence of zero or span gas supply.
Verify the supply of zero and span gasses
Incorrect manual calibration procedure.
Conduct zero and span calibration again
Sensor drift or characteristic changes over time.
If calibration coefficients are outside specifications due to sensor issues, initialize calibration coefficients and conduct zero and span calibration again
Fluctuations in O2 Readings
Possible Causes
Troubleshooting Steps
Inconsistent flow rate of sample gas.
Verify and stabilize the flow rate of the sample gas.
Leaks in piping joints or connections between auxiliary gas cylinder and analyzer.
Inspect piping joints and connections for leaks; rectify if found.
Instability in constant temperature chamber temperature.
Ensure constant temperature chamber maintains stability
Fluctuations in power supply voltage
Monitor and address fluctuations in power supply voltage
Exposure to direct sunlight or radiant heat from a heat source.
Protect analyzer from direct sunlight or radiant heat.
Drift in Oxygen Readings
Possible Causes
Troubleshooting Steps
Inappropriate supply pressure of auxiliary gas
Check and adjust auxiliary gas pressure to ensure it meets specifications
Short-Term Shift in Readings
Possible Causes
Troubleshooting Steps
Inconsistent or unstable flow rate of sample gas
Verify and stabilize the flow rate of the sample gas. If flow of sample gas containing oxygen is turned off or closed or blocked, confirm and rectify the issue
Calibration Cannot be Executed
Possible Causes
Troubleshooting Steps
The analyzer is not in a stable condition
Wait for the analyzer to reach a steady state before attempting calibration.
Improper calibration gas concentrations configured in the analyzer.
Verify and adjust calibration gas concentrations setting according to analyzer specifications.
Incorrect Nominal Value of Span Gas
Verify the nominal value of the span gas and compare it with the certification provided with the span gas cylinder. Correct any discrepancies in the entered value.
Incorrect Zero Gas / Span Gas in Use
Verify that the correct zero gas and span gas are being used for calibration purposes. Replace with the appropriate gasses if necessary.
Incorrect Physical Zero Point
Verify the physical zero point alignment of the instrument and make necessary adjustments as per the instructions provided in the manual.
Contamination of the Gas Paths
Inspect the components for any contamination or dirt. Clean or replace the components as required to ensure proper functioning. Adjust physical zero point alignment if necessary.
Analyzer has no Function (local LCD display is dark)
Possible Causes
Troubleshooting Steps
External supply voltage is absent
Inspect and ensure proper connection of mains line.
External power supply for not in correct DC polarity.
Check external power supply for correct DC polarity.
Possible internal failures in circuit
Verify internal voltage supply and internal fuses
Internal connections incorrect or absent
Ensure PCB is correctly placed. Check and re-establish proper connection of PCB’s and other cable with connectors
LCD display defective
Replace front panel to rectify issues with PCB in the display unit or defective LCD display
No / Incorrect Measurement Screen (In Remote)
Possible Causes
Troubleshooting Steps
Defective network connection
Inspect network termination for any issues
Verify network connection between analyzer and external modules.
Verify and rectify network connections between platform, analyzer, and external modules. Replace connection cable or network module
Analyzer module has not been integrated:
Refer to the software manual and follow instructions to integrate the analyzer module into the system software.
Failure in signal processing
Review troubleshooting steps outlined in analyzer manual to address any signal processing failures.
Incorrect wiring and external factors
Verify external wiring connections and rectify any issues causing electromagnetic radiation
Raw Signal Too High / Low
Possible Causes
Troubleshooting Steps
Concentration of sample gas is too high
Adjust the gas concentration to within the analyzer’s specified rangeIf the concentration cannot be adjusted, consider using an alternative analyzer designed for higher concentrations
Incorrect physical zero point
Ensure the zero point is correctly aligned to improve accuracy of the raw signal
Contamination of the gas paths
Clean or replace contaminated components as required. Check and adjust physical zero point alignment as contamination may affect alignment.
No or Incorrect Analog Outputs / Digital I/O’s
Possible Causes
Troubleshooting Steps
Configuration of Digital, analog Input/output signals incorrect.
Verify the configuration settings of Input/output signals and ensure they align with the required specifications. Make necessary adjustments as per the system requirements.
Incorrect wiring and electromagnetic interference
Review the wiring of external factors connected to the Input/output signals to ensure they are correctly wired and shielded to prevent electromagnetic interference
Inaccurate O2 Concentration
Possible Causes
Troubleshooting Steps
Leakage into Gas Circuit
Conduct a thorough leakage check according to the guidelines provided in the manual. Repair any leaks found to prevent gas loss.
Ambient Air Contains Excessive Gas Constituents
Ensure proper purging of the instrument to remove ambient air. Adjust purging procedures as necessary to prevent excessive gas constituents
Gas Pressure Subject to Excessive Fluctuations
Inspect gas lines for restrictions and eliminate them beyond the gas outlet fitting and filter. Adjust pumping or flow rates to stabilize gas pressure
Contamination of Gas Paths
Inspect sensing components for contamination. Clean or replace components as needed to ensure accurate readings.
Temperature Below Dew Point
Monitor and adjust gas paths’ temperature to prevent condensation. Clean or exchange gas conditioning components if necessary.
Response Time Too Long
Possible Causes
Troubleshooting Steps
Incorrect Response Time
Review the software manual to verify the configured value for Response Time . Adjust the settings if necessary to match the desired response time.
Inadequate Pumping Rate
Check the gas sampling pump’s diaphragms and membranes for any damage or wear. If necessary, replace them. Consider using a larger external pump or adding a bypass line to shorten the sampling distance.
Contamination of Gas Paths
Inspect components for contamination. Clean or replace components as required to ensure unobstructed gas flow and accurate readings.
Troubleshooting Summary
Consider environmental factors that could affect the analyzer’s performance, such as temperature fluctuations, humidity, and exposure to contaminants.
Implement a regular maintenance schedule to prevent issues before they occur. This includes cleaning, calibration, and replacement of worn-out components as needed.
By following these steps and consulting the manufacturer’s guidelines, you can effectively troubleshoot faults with an oxygen analyzer and ensure accurate and reliable readings.
With over 24 years of dedicated experience, I am a seasoned professional specializing in the commissioning, maintenance, and installation of Electrical, Instrumentation and Control systems. My expertise extends across a spectrum of industries, including Power stations, Oil and Gas, Aluminium, Utilities, Steel and Continuous process industries. Tweet me @sundareshinfohe
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