How to

Troubleshooting of Oxygen Analyzer : Paramagnetic Type

  • Because oxygen has two unpaired electrons, it is paramagnetic, or sensitive to magnetic fields, unlike most other gasses. 
  • This characteristic allows for the highly accurate detection of the gas by magnetic analyzers. 
  • These devices have their sensors fixed or suspended inside a magnetic field. 
  • The presence of oxygen in a sample will cause the sensors to move because oxygen molecules are drawn to magnets. 
  • The amount of oxygen present corresponds directly with the extent of this displacement, as determined by the current required for correcting it.

Click here to know more about Working Principle of Paramagnetic O2 Analyzers 

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

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 CausesTroubleshooting Steps
Drop in auxiliary gas pressureCheck auxiliary gas pressure to ensure it meets specifications with the instrument data sheet.
Excessive flow rate of the sample gasVerify sample gas flow rate to ensure it is within specified limits as per the manufacturer guidelines
Sensor faulty or not working properlyVerify 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 Sampling System
Possible CausesTroubleshooting Steps
Sampling System CheckVerify 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 SystemInvestigate gas sampling integrity, checking for leaks or blockages.Ensure gas sampled accurately represents the environment.
  • 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 CausesTroubleshooting 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 systemInvestigate heater connection and internal thermostat actionCheck heater power control components . If a still error occurs, verify internal thermostat activation at specified range (70°C.)

An analog error occurs when there is a failure in the analog circuit

Possible CausesTroubleshooting Steps
Failure in the analog circuitTurn off the power and restart the AnalyzerIf error persists, replace the analog card  and contact the service center for assistance.

A memory error occurs if there is a failure in reading or writing the memory device. 

Possible CausesTroubleshooting 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 error occurs when the obtained calibration coefficient is outside the normal range.

Possible CausesTroubleshooting Steps
Calibration gas concentration mismatch.Identify and rectify calibration gas concentration discrepancies
Low pressure of auxiliary gasEnsure 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
Possible CausesTroubleshooting 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 voltageMonitor 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.
Possible CausesTroubleshooting Steps
Inappropriate supply pressure of auxiliary gasCheck and adjust auxiliary gas pressure to ensure it meets specifications
Possible CausesTroubleshooting Steps
Inconsistent or unstable flow rate of sample gasVerify 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
Possible CausesTroubleshooting Steps
The analyzer is not in a stable conditionWait 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 GasVerify 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 UseVerify that the correct zero gas and span gas are being used for calibration purposes. Replace with the appropriate gasses if necessary.
Incorrect Physical Zero PointVerify the physical zero point alignment of the instrument and make necessary adjustments as per the instructions provided in the manual.
Contamination of the Gas PathsInspect 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.

Click here to carry out 10 Step Oxygen Analyzer Calibration Procedure: Paramagnetic Type

Possible CausesTroubleshooting Steps
External supply voltage is absentInspect 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 absentEnsure PCB is correctly placed. Check and re-establish proper connection of PCB’s  and other cable with connectors
LCD display defectiveReplace front panel to rectify issues with PCB in the display unit  or defective LCD display
Possible CausesTroubleshooting Steps
Defective network connectionInspect 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 processingReview troubleshooting steps outlined in analyzer manual to address any signal processing failures.
Incorrect wiring  and  external factorsVerify external wiring connections and rectify any issues causing electromagnetic radiation 
Possible CausesTroubleshooting Steps
Concentration of sample gas is too highAdjust 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 pointEnsure the zero point is correctly aligned to improve accuracy of the raw signal
Contamination of the gas pathsClean or replace contaminated components as required. Check and adjust physical zero point alignment as contamination may affect alignment.
Possible CausesTroubleshooting 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 interferenceReview the wiring of external factors connected to the Input/output signals to ensure they are correctly wired and shielded to prevent electromagnetic interference
Possible CausesTroubleshooting Steps
Leakage into Gas CircuitConduct 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 ConstituentsEnsure proper purging of the instrument to remove ambient air. Adjust purging procedures as necessary to prevent excessive gas constituents
Gas Pressure Subject to Excessive FluctuationsInspect 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 PathsInspect sensing components for contamination. Clean or replace components as needed to ensure accurate readings.
Temperature Below Dew PointMonitor and adjust gas paths’ temperature to prevent condensation. Clean or exchange gas conditioning components if necessary.
Possible CausesTroubleshooting 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 RateCheck 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 PathsInspect components for contamination. Clean or replace components as required to ensure unobstructed gas flow and accurate readings.
  • 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.

Click here for Step by Step Preventive Maintenance Procedure for O2 Analyzers : Paramagnetic Type

Click here to download the Checklist to carry out Step by Step Preventive Maintenance 

  • 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.

Click here for 50+ Instrumentation and Control System Troubleshooting Procedure

Sundareswaran Iyalunaidu

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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