10 Step Oxygen Analyzer Calibration Procedure: Paramagnetic Type

  • A paramagnetic type oxygen analyzer is a device used for measuring the concentration of oxygen in a gas mixture. 
  • It relies on the paramagnetic properties of oxygen molecules, which means that oxygen is attracted to a magnetic field. 
  • The analyzer uses this property to detect and quantify the amount of oxygen in a sample.
  • Paramagnetic analyzers are known for their high precision and sensitivity in measuring oxygen levels, making them valuable in various applications such as industrial processes, environmental monitoring, and medical settings. 
  • They are particularly useful in situations where accurate and reliable measurement of oxygen concentration is crucial.
  • The following step-by-step calibration procedure offers a comprehensive guide on calibrating a Paramagnetic type Oxygen Analyzer in a process area or analyzer room using sample zero and span gas cylinders. 
  • It provides a detailed explanation of the calibration process, ensuring accurate and reliable measurements of oxygen concentration.
Prepare the Tools Required for Paramagnetic type O2 Analyzer Calibration
  1. Sample Zero Gas Cylinder
  2. Span Gas Cylinder
  3. Calibration Documentation Forms
  4. O2 Analyzer data sheet / Specifications
  5. Communication Tools if necessary
  6. Calibration Gas Regulator
  7. Tubing and Connectors
  8. Necessary safety gear (e.g., gloves, safety goggles)
  9. Standard Tools and Cylinder Key
  • For additional insights into the recommended calibration process and essential safety considerations in the process industry, please visit the following page: 

Process Industry Calibration Methodology: Essential Safety and General Considerations.

  • Ask the panel operator to set the controller’s MOS (Maintenance Override Switch) to manual mode for the Paramagnetic Oxygen Analyzer.
  • Check if the Paramagnetic Analyzer is integrated into an Emergency Shutdown (ESD) loop.
  • Confirm any specific procedures related to the ESD system outlined in safety documentation.
  • Identify and locate the specific Paramagnetic Oxygen Analyzer that requires calibration.
  • Confirm the analyzer’s details, such as tag number, manufacturer, model number, and any relevant information.
  • Adapt the fundamental safety approach based on the unique characteristics of the Paramagnetic Analyzer and the process location.
  • Strictly adhere to local safety regulations and the manufacturer’s instructions when working with the Paramagnetic Oxygen Analyzer.
  • Implement lockout/tagout procedures to prevent inadvertent activation of the analyzer during calibration.
  • Ensure effective isolation of the Paramagnetic Analyzer from the process to prevent safety hazards.
  • Prioritize the use of proper personal protective equipment (PPE) during the calibration process.
  • Be careful when handling the Paramagnetic Analyzer, and make sure to stay away from the situation and follow safety precautions.
  • To maintain a safe working environment, provide safety training and awareness to everyone involved in the calibration of Paramagnetic type O2 Analyzers.
Calibration Setup for Paramagnetic type O2 Analyzer
  • Ensure that the location that was selected for Paramagnetic type Oxygen Analyzer calibration, as well as the calibration tools, are free of electromagnetic interference and vibrations. 
  • Additionally, ensure that the calibration environment is well-lit and appropriately ventilated to allow for a safe and accurate calibration process.
  • Collect all of the tools and supplies needed for calibrating the Paramagnetic Oxygen Analyzer. 
  • Refer to the analyzer’s documentation and instrument loop diagram for specific requirements.
  • Turn off the power of the Paramagnetic Analyzer.
  • Close the sample inlet needle valve to the analyzer as shown in the  figure.
  • Disconnect the gas plant sample tubing connected to the analyzer if necessary.

NOTE: Set the pressure of the auxiliary gas to the specified pressure as stated on the nameplate on the inside of the instrument panel or instrument data sheet of the analyzer.

  • Use nitrogen with a minimum purity of 99.99% as the zero gas. 
  • Use a gas having an oxygen content of 80–100% of the upper range value of the specified range as the span gas (for example, 20–25% oxygen should be used for the range of 0 to 25%) as per the data sheet of the analyzer manufacturer.
  • Mount the pressure regulator assembly with the pressure regulating valve and needle valve on the calibration cylinder.
  • When setting up the calibration process for the Paramagnetic type Oxygen Analyzer, it is imperative to ensure that the calibration gas cylinder used is certified.
  • Look for specific details on the certification label, including the certification date, expiration date (if applicable), and the name of the certifying Agency
  • Confirm that the oxygen concentration in the calibration gas matches the specified concentration mentioned on the certification label..
  • Ensure that the pressure regulator is set to deliver gas at an outlet pressure not exceeding 0.5 bar(g) or as per the data sheet of the analyzer manufacturer.
  • Connect the tube from the pressure regulator outlet to the back of the analyzer at the port labeled “IN. or calibration gas isolation valve in the analyzer room.
  • Power on  the analyzer  and allow it to go through a warm-up period until it reaches a steady state as per the manufacturer instruction.
  • During warm-up, the instrument controls the sensor unit temperature to stabilize at 60 °C.
  • The amount of time needed varies according to the ambient temperature or the sensor unit’s starting temperature.
  • calibration cannot be executed in this during this period
Instrument Warm-Up and stabilization o2 analyzer
  • Calibration involves a 2-point calibration with zero calibration (using zero gas – nitrogen with 0% oxygen) and span calibration (using span gas with a known oxygen concentration).
  • Calibration modes include measuring mode, maintenance mode has zero calibration mode and span calibration mode.
Zero Calibration of Paramagnetic type O2 Analyzer 
  • Ensure the analyzer is switched to maintenance mode to facilitate calibration.
  • Open the calibration gas isolation valve to allow the flow of calibration gas to the analyzer. This step is crucial for introducing the known concentration gas to the system.
  • Open the zero gas cylinder containing nitrogen.
  • Allow the analyzer to stabilize, ensuring that the zero calibration is performed accurately.
  • Observe specified flow rate in rotameter(flowmeter with regulation) as per the instrument datasheet of analyzer.
  • Observe and record the readings displayed on the analyzer.
  • After completing the zero calibration, close the calibration gas isolation valve to stop the flow of calibration gas.
  • During zero calibration, note the 4 mA output value.
  • Using a multimeter, measure the current output from the analyzer and compare it with the expected 4 mA during zero calibration.
  • Observe the concentration values displayed on the analyzer and in the control room  during zero calibration.
  • Compare these values with the expected zero concentration based on the use of the zero gas (e.g., nitrogen).
  • Refer the instrument data sheet for the analyzer to verify the expected range of readings during zero calibration.
  • Ensure that the readings fall within the specified range and meet the instrument’s accuracy criteria for zero calibration as per the calibration control plan.
  • If errors are identified in  zero calibration readings, adjust the analyzer parameters accordingly to align with the calibration values and instrument specifications.
  • After completing the zero calibration, close the calibration gas isolation valve to stop the flow of calibration gas and also close the zero gas cylinder containing nitrogen.
  • Open the span gas cylinder containing the known concentration gas (e.g., 25% span gas).
  • Open the calibration gas isolation valve and apply the span gas at the specified flow rate
  • Allow the analyzer to stabilize, ensuring that the span calibration is performed accurately.
  • Observe the concentration values displayed on the analyzer during both span calibration.
  • Compare these values with the expected concentrations based on the known calibration gas concentrations
  • Consult the instrument data sheet for the analyzer to verify the expected range of readings for span calibration.
  • Ensure that the readings fall within the specified range and meet the instrument’s accuracy criteria as per the calibration control plan.
  • During span calibration, note the measured mA output value.
  • Using a multimeter, measure the current output from the analyzer and compare it with the expected mA during span calibration
  • Consult the instrument data sheet for the analyzer to verify the expected range of readings during span calibration.
  • Ensure that the readings fall within the specified range and meet the instrument’s accuracy criteria for span calibration as per calibration control plan.
  • If errors are identified in span calibration readings, adjust the analyzer parameters accordingly to align with the calibration values and instrument specifications.
  • After completing the Span calibration, close the calibration gas isolation valve to stop the flow of calibration gas and also close the span gas cylinder containing nitrogen + oxygen.
  • Conduct multiple calibration runs to check for repeatability. Repeat the zero and span calibration procedures.
  • Verify that the instrument readings are consistent across multiple calibration runs. Repeated runs should produce similar results.
  • If the repeatability checks reveal that the oxygen (O2) analyzer does not meet acceptable standards, corrective actions should be taken.
  • After repairs or replacement, conduct thorough tests to verify that the repeatability issue has been resolved
 Calibration of Paramagnetic type O2 Analyzer 
  • When the calibration is successful, attach a label with the date, personnel, and calibration data to the O2 analyzer.
  • Make sure the O2 analyzer equipment is completely clean and free of any residues. Place the equipment in its appropriate storage area and keep it safe.
  • Keep a record of all relevant calibration information, such as the starting and ending readings, any changes that were carried out, and any identified errors. Store this data in the analyzer log for future use.
  • Open the sample gas valve to allow the flow of the gas you intend to measure.
  • After calibration, the analyzer should be purged with sample gas.The purge time refers to the time it takes for sample gas to pass through the sensor unit and remove calibration gas after calibration as per the manufacturer recommendation.
  • Set the analyzer to measuring mode to begin obtaining readings from the sample gas.
  • Remove any isolation measures or barriers implemented during calibration.
  • Allow the O2 analyzer to resume regular operation within the processing area.
  • Confirm that the O2 analyzer provides accurate and reliable measurements in real time. Compare the current data to the expected values based on the calibration.
  • Ensure safety interlocks or control systems are normalized.
  • Confirm that any temporarily modified or interrupted interlock systems are restored to their standard operational configurations.
  • Create a calibration report for the O2 analyzer.
  • Clearly outline the calibration process, including the gasses used and any adjustments made.
  • Use a standardized template in Excel for organized documentation.
  • Ensure the report captures crucial details for future reference and maintenance. Refer the below sample calibration report of paramagnetic oxygen analyzer.
  Calibration of Paramagnetic type O2 Analyzer  1
  • Our precision-focused procedure ensures accurate O2 concentration measurements in industrial settings.
  • Adheres to NIST standards for exceptional measurement accuracy.
  • IEC 61508 compliance ensures systematic safety across the analyzer’s lifecycle.
  • Comprehensive calibration method, inclusive of our practices, enhances accuracy, aligns with industry best practices.
  • ISO/IEC 17025 compliance ensures competence in testing and calibration labs.
  • Follows ISO 6143 for precise calibration gas mixtures in O2 analyzers.
  • Aligns with industry standards for reliable O2 concentration measurements.

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