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

  • Paramagnetic O2 analyzers are essential in many industries because they enable precise monitoring of oxygen concentration in a variety of gas mixes. 
  • Precise preventive maintenance is necessary to ensure the accuracy, lifespan, and peak performance of these trustworthy equipment. 
  • You can extend the lifespan of the analyzer, reduce downtime, and ensure data integrity by following a thorough maintenance plan.
  • The following guide explores all the important facets of paramagnetic O2 analyzer preventive maintenance, giving you the information and tools you need to maintain the best possible performance from your analyzer.
  • Let’s explore the principles of these instruments before getting into the details. 
  • The paramagnetism of oxygen molecules is a special quality that is utilized by paramagnetic O2 analyzers. 
  • This property pulls oxygen to the sensor’s intense magnetic field. The force that this attraction produces on the sensor is measured by the analyzer and has a direct relationship with the amount of oxygen present in the sample gas. 
  • They vary from other kinds of O2 analyzers in that they operate on this concept, which makes them especially appropriate for applications demanding high sensitivity and quick response times, as well as hazardous gas mixtures.

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

  • Instruct the panel operator to set the MOS (maintenance override switch) for both manual mode of the controllers’ (Paramagnetic O2 analyzers control loop) and ESD loop prior to initiating any PM tasks on the Paramagnetic O2 analyzers.
  • Make that the system’s sample impulse tubes and calibration gas line are depressurized using the proper techniques before maintaining the O2 analyzer. (e.g., closing the main sample inlet isolation valve of Paramagnetic O2 analyzers).
  • Refer to the instrument loop diagram to locate adjacent junction boxes or Marshaling Cabinets near the control room for isolating and power off the Paramagnetic O2 analyzers.
  • This approach may require changes based on the type of equipment and process location of the Paramagnetic O2 analyzers.
  • Always adhere to the manufacturer’s guidelines and local safety standards when working with Paramagnetic O2 analyzers or any process equipment. This includes wearing additional PPE, utilizing specific tools, or following safety protocols.
  • To avoid exposure or environmental harm, recognize and deal with any hazardous materials or chemicals near the Paramagnetic O2 analyzers using the correct handling, storage, and disposal methods.
  • Wear the proper PPE, such as gloves, safety glasses, and protective clothes, in accordance with the company’s safety procedures. Evaluate the particular risks related to the maintenance tasks.
  • To avoid unintentional restart, adhere to lockout/tagout protocols. When doing preventative maintenance, keep the Paramagnetic O2 analyzers inactive.
  • Examine relevant procedure documents for information on hazardous materials, such as SDSs, P&IDs, and SOPs.
  • Make sure that other personnel are informed of the safety precautions while discussing maintenance work on the Paramagnetic O2 analyzers. This includes talking to supervisors and maintenance technicians.
  • Request for work permit for PM tasks on Paramagnetic O2 analyzers.
  • Visual Examination: Regularly inspect the analyzer for any physical harm, leaks, loose connections, or accumulation of dust around the inlet/outlet and filters. Address any abnormalities promptly.
  • Power Supply: Ensure a stable power supply within the specified voltage range, as voltage fluctuations can affect measurement accuracy.
  • Wiring Inspection: Inspect the wiring of the Paramagnetic O2 Analyzers to ensure all connections terminals are secure and free from corrosion or damage.
  • Power Source Check: Check the power source of the Paramagnetic O2 Analyzers to ensure it operates within the recommended voltage range, by measuring the supply voltage with a multimeter.
  • Grounding Verification: Verify proper grounding of the Paramagnetic O2 Analyzers by checking resistance to ground with a multimeter.
  • Housing Examination: Examine the housing of the Paramagnetic O2 Analyzers for signs of wear or damage, including fractures that could compromise operation.
  • Analog Signal and Communication Check: Verify the integrity of analog signals and communication wiring connections to ensure accurate data transmission.
  • Digital Signal Wiring Inspection: Inspect the digital signal wiring to ensure proper connections and functionality for effective communication.
  • Internal Component Inspection: Check for wear, contamination, or damage internally, if at all possible, on crucial parts including the sensor chamber, magnet assembly, and electronics. Prevent performance degradation by quickly fixing any faults identified during the inspection.
  • Check and Confirm analyzer operates within specified temperature and humidity limits.
  • Regularly monitor and adjust environmental conditions as needed to maintain optimal performance.
  • Thoroughly inspect analyzer exterior for any accumulation of debris or dust.
  • Utilize appropriate cleaning tools, such as a cloth or brush, to gently remove debris from surfaces and openings.
  • Evaluate surroundings for potential sources of interference, including electromagnetic fields, vibrations, and temperature fluctuations.
  • Take proactive measures to minimize or eliminate interference effects, such as relocating nearby equipment or installing shielding.
  • Continuously monitor environmental conditions to ensure ongoing stability and accuracy of analyzer readings.
  • Change filters on a regular basis in accordance with the application conditions and manufacturer’s recommendations. Take into account variables like usage frequency and the amount of dust present in the sample gas. Clogged filters limit flow and decrease measurement accuracy.
  • To remove impurities efficiently without obstructing the intended flow rate, use filters with the right pore size. Measurements may be affected if vital components of the sample gas are trapped by improper pore size.
  • The leak tightness of both the sample gas path and, if applicable, the reference gas path, should be verified at least annually during operation.
  • Specifically, it’s crucial to check the leak tightness of the sample gas path each time it’s opened within the gas analyzer.
  • Verify that the auxiliary gas is supplied at the specified pressure, checking the pressure gauge on the gas cylinder and in the aux gas line  if applicable. Replace the gas cylinder if the pressure is low.
  • Measure and Ensure that the primary pressure of the supplied pressure regulator for auxiliary gas is at least 300 kPa as per the manufacturer recommendation.

Caution: Conduct zero and span calibrations when readjusting the auxiliary gas pressure.

  • Regularly monitor the flow rate of the sample gas to ensure proper operation refer the manufacturer recommendation.
  • Inspect seals, gaskets, and O-rings in the analyzer’s housing and sample gas path for signs of wear, deterioration, or leaks. Replace any damaged seals to maintain gas-tight integrity and prevent sample gas leaks that could affect measurement accuracy.
  • It is important to be careful when stopping and continuing the operation in order to avoid common problems.
  • When sample gas contains corrosive components, turn off the flow with auxiliary gas supplied and purge the sample gas line with nitrogen gas or instrument air.
  • Ideally, allow auxiliary gas to flow while the operation is suspended.
  • Before restarting, check the sample gas line for moisture and purge with instrument air if necessary to prevent sensor unit failure.

Click her to know more about about Working Principle of Gas Sampling System for Gas Analyzers 

  • Verify parameters by referring to Instrument Data Sheets or commissioning reports of the Paramagnetic O2 Analyzers.
  • Ensure Analyzers are running on the latest software version by checking for firmware upgrades.
  • Periodically verify the performance of the paramagnetic sensor by conducting functional tests  using certified gas standards. 
  • This ensures that the sensor’s response remains accurate and within acceptable limits.
  • Regular calibration ensures the accuracy of the analyzer by adjusting its response to match known oxygen concentrations, effectively correcting any drifts in measurements that may occur over time.
  • The frequency of calibration depends on various factors such as the manufacturer’s guidelines, specific application requirements, demands for accuracy, and the stability of the analyzer itself. 
  • Critical applications with tight accuracy tolerances may necessitate more frequent calibration compared to others.
  • It is essential to use certified calibration gasses with the appropriate concentration range that matches the specific application and measurement requirements.
  • Following the calibration procedure outlined in the manufacturer’s manual is important. 
  • Following the correct steps ensures that the calibration is performed accurately and effectively, maintaining the precision of the analyzer’s measurements.

Click here to carry out Calibration of Paramagnetic O2 Analyzers

  • Test the analyzer’s response time to variations in oxygen concentration by creating step changes in the sample gas. 
  • Make that the analyzer reacts to changes quickly and properly; if it takes a while, there may be a problem with the sensor or other concerns.
  • Continuously monitor for drift in measurement readings over time. Abnormal or significant drift could be a sign of problems with the stability of the sensor, contaminated sample gas, or other problems influencing the analyzer’s performance. 
  • Address drift through recalibration or troubleshooting as necessary.
  • Employing a zero gas filter when the analyzer is not in use can help protect the sensor from contamination by ambient air. This practice can extend the sensor’s lifespan and improve measurement accuracy upon startup.
  • It is important to avoid exposing the analyzer to corrosive gasses or harsh chemicals, as these substances can damage the sensor and other components over time. If exposure to such substances is unavoidable, consider implementing appropriate filtering or isolation measures to safeguard the analyzer.
  • In the event of any issues with the analyzer’s performance, such as erratic readings or unexpected behavior, it is recommended to promptly contact a qualified Analyzer technician for professional troubleshooting and repair. 
  • Maintaining a logbook to document all maintenance activities performed on the analyzer is essential. 
  • The logbook should include detailed records such as dates of maintenance, readings, calibration gas details, any corrective actions taken, and notes on observed issues. 
  • Keeping detailed records facilitates trend analysis, scheduling of preventive maintenance tasks, and effective troubleshooting.
  • Always refer to the manufacturer’s manual for specific maintenance instructions and recommendations tailored to the particular oxygen analyzer being used.
  • After performing any maintenance procedures, it is important to calibrate the analyzer to ensure accurate measurements.
  • Following the completion of the PM (preventive maintenance) for the analyzing system, it is advisable to clean the tools and equipment used, store them securely, and make a note of the details from the PM checklist for future reference.
  • Additionally, it is essential to ensure that the workspace used for PM on the analyzing system is kept neatly organized, facilitating efficient maintenance activities and ensuring the integrity of the analyzer’s operation.
  • De-isolate the equipment and resume the sample supply system after conducting a PM on the O2 Analyzer system.
  • Restore the bypassed or disabled signal of the O2 Analyzer system to its original level.
  • Make sure the  O2 Analyzer system is in good working order before utilizing it.

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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