Analytical Instrumentation

Conductivity Transmitter / Analyzer Preventive Maintenance Guide & Checklist

To ensure accuracy and minimize downtime, every  conductivity transmitter needs some amount of routine maintenance. You should plan your maintenance schedule in accordance with the requirements of each conductivity transmitter.

  • Ask the panel operator to configure the MOS (maintenance override switch) for the controllers’ manual mode (conductivity transmitter control loop) and ESD loop, respectively. 
  • Both of these parameters must be simultaneously configured before starting any PM activity on the conductivity transmitter.
  • Locate the conductivity transmitter for which you want to do PM maintenance.
  • Before PM the conductivity transmitter, you might need to drain the conductivity transmitter as well as the system’s sample impulse tubes.
  • Depressurize the system using suitable techniques (such as by closing the main sample inlet isolation valve of conductivity transmitter).
  • You can locate the power supply source for isolation by using an instrument loop diagram  to look for any nearby junction boxes or Marshalling Cabinets near the control room. 
  • This method may need to be modified depending on the conductivity transmitter’s equipment and process location.
  • When working with a conductivity transmitter or any other piece of process equipment, it is essential that you always adhere to the instructions provided by the manufacturer as well as the regional safety standards. 
  • This may include wearing additional PPE, using specific tools or equipment, or following specific safety protocols.
  • Follow lockout/tagout protocols to avoid unintentional starts. Keep the conductivity transmitter out of the process for preventative maintenance.
  • Review process documentation related to the conductivity transmitter, such as piping and instrumentation diagrams (P&IDs), standard operating procedures (SOPs), and safety data sheets (SDSs) for any hazardous materials that may be present.
  • Coordinate with other plant personnel who may be affected by the maintenance work, such as operators or maintenance technicians. Ensure that they are aware of the work being performed and any safety precautions that need to be taken.
  • Depending on the nature of the maintenance work, you may need to obtain permits from the plant’s safety department.
  • Ensure that maintenance personnel are trained in emergency response procedures, including how to respond to chemical spills, fires, or other emergencies that may occur during maintenance activities.
  • Check all connections in the sampling system for leaks. This includes the sampling probe, sample line, and any valves or fittings. Search for any indications of corrosion or damage.
  • Clean the sampling system to remove any build-up or debris that may be affecting the accuracy of the conductivity readings.This can need the use of specialist cleaning materials or equipment.
  • Check the sampling probe for any signs of damage or wear. This includes the probe tip, which may become worn or damaged over time and affect the accuracy of the conductivity readings.
  • Inspect the sample line for any signs of damage or wear. This includes checking for kinks, bends, or other obstructions that may be affecting the flow of the sample.
  • Check the pressure and flow rate of the sample to ensure that it is within the recommended range. This may involve using a flow meter or other specialized equipment to measure the flow rate.
  • Clean the transmitter to remove any dust, dirt, or other debris that may be affecting its performance. This may involve using a soft cloth or brush to clean the exterior of the transmitter.
  • Inspect the wiring of the transmitter to ensure that all connections are tight and secure. Look for any signs of corrosion or damage to the wiring and termination in the conductivity analyzer.
  • Check the power supply of the transmitter to ensure that it is operating within the recommended voltage range with help of multimeter. 
  • Check the grounding of the transmitter to ensure that it is properly grounded. This may involve using a calibrated multimeter to measure the resistance to ground.
  • Inspect the transmitter housing for any signs of damage or wear. Look for any cracks or other damage that may be affecting the performance of the transmitter.
  • Verify the parameter with an instrument data sheet or commissioning report of the conductivity transmitter.
  • Check for firmware updates for the transmitter and ensure that it is up to date with the latest software.
  • Verify function of the conductivity transmitter using resistance simulation with decade resistance box. Please refer the the below link for the calibration of conductivity transmitter with decade resistance box,

Click here to carry out calibration of conductivity transmitter with decade resistance box

  • To ensure that the conductivity values are accurate, clean the measuring cell of any buildup or debris. Utilizing a specialized cleaning solution or tool in accordance with the type and manufacturer’s recommendations.
  • Warm water, dishwashing detergent, Borax hand soap, or a comparable soap should be combined to make a mild soap solution.
  • Check the sensor on a regular basis for debris and deposits. 
  • If deposits have accumulated or the sensor’s performance has declined, clean it. 
  • To clean out any loose debris from the sensor’s end, use a clean, soft cloth. Wash the sensor in warm, clean water.
  • Soak the sensor in a soap solution for two to three minutes.
  • Scrub the entire measuring end of the sensor with a soft-bristle brush.
  • If debris is still present, immerse the sensor’s measurement end for no longer than five minutes in a diluted acid solution, such as one that contains 5% HCl.
  • After cleaning the sensor with water, put it back in the soap solution for two to three minutes.
  • Rinse the sensor with some water so that it may be made clean.
  • Examine the measurement cell for any indications of wear or damage. Look for any damage that might be compromising the accuracy of the conductivity readings, such as cracks, scratches, or other flaws.
  • Make sure the electrode spacing is within the recommended range by verifying it. This can involve measuring the distance between the electrodes with a specialized tool as per the manufacturer recommendation.
  • To make sure the conductivity transmitter is giving reliable readings, calibrate it. To confirm the correctness of the readings, this can entail utilizing a reference guide or a standard solution.  To calibrate a conductivity transmitter using standard solutions, please click the link below.

 Click here to carry out calibration of conductivity transmitter with standard solutions

  • Verify that the temperature compensation is functioning properly. This may involve using a temperature sensor to measure the temperature of the solution being monitored and verifying that the transmitter is compensating for any changes in temperature.
  • Inspect the cable connection between the measuring cell and the transmitter to ensure that it is secure and free of any damage. Look for any signs of corrosion or wear on the cable connection.
  • Check the insulation resistance of the measuring cell to ensure that it is within the recommended range. This can include measuring the resistance using a multimeter.
  • Surface connection measurement: The sensor connector’s connectors are directly attached to the measurement surfaces. Check with multimeter at less than 1Ω.
  • Surface shunt measurement: A shunt between the measurement surfaces might not exist. Multimeter readings more than 20 M ohms  should be checked.
  • Shunt for temperature sensors: Between the measuring surfaces and the temperature sensor, there might not be any shunt. Check with a multimeter at more than 20 M ohms.
  • Temperature sensor output: Consult the sensor nameplate to determine the type of temperature sensor being utilized. Using an ohmmeter, the sensor can be tested at the sensor connector as follows:

PT 100 at 25 °C (77 °F) = 109.79 Ohms

PT 1000 at 25 °C (77 °F) = 1097.9 Ohms

NTC 10k at 25 °C (77 °F) = 10 kilo Ohms

  • Check for moisture (pay attention to the effect on low conductivity measurements, dry the box if necessary, replace the seals and insert a drying bag).
  • Check that every line is correctly wired according to the diagram.
  • Fastening and securing the cable outer screens.
  • Verify the degree of tightness of the terminal screws.
  • The accuracy of the measurement could be impacted by the environment surrounding the conductivity transmitter’s temperature and humidity conditions. 
  • Maintain Experts in maintenance suggest positioning the conductivity transmitter in a stable location apart from sources of heat and moisture.  
  • They must also regularly examine the ambient conditions to ensure that they remain within the conductivity transmitter’s allowed range.
  • It is essential to maintain accurate records of all maintenance chores, calibration dates, and any issues with or repairs performed to the conductivity analyzing system in order to troubleshoot and spot trends in the functioning of the conductivity transmitter. 
  • The maintenance team for the conductivity analyzer should record this information in a logbook or database so that it may be used for analysis and reporting.

Click here for How to do troubleshooting of conductivity transmitter

  • After performing any maintenance procedures, you should always calibrate the sensor.
  • After the conductivity analyzing system PM is finished, clean the tools and equipment, store it safely, and write down any pertinent information from the PM checklist for later use.
  • Verify that the conductivity analyzing system has been kept properly organized at the PM’s workspace.
  • Once a PM has been performed on the conductivity measurement system, de-isolate the equipment and resume the sample supply system. 
  • Verify the conductivity analyzer sample flow and should not have any bubbles.
  • Restore the bypassed or disabled signal of the conductivity analysis equipment to its original level.
  • Make sure the conductivity analysis system is in good working order before utilizing it.

Click here for Collection of Preventive Maintenance (PM) Procedures for Instrumentation and Control Systems

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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