Ph Sensor Diagram: Knowing Your Ph
When troubleshooting pH, ORP, and oxygen sensors, you can utilise the Sensor Diagram to quickly assess the state of your connected sensor. The pH Sensor Diagram is a special feature of the Portavo 907 & 908 portable metres, as well as the Stratos Multi and Protos transmitters. Information about continuously monitored sensor parameters is displayed in the diagram. The diagram’s parameter values must fall within the outside 100% and inner 50%. The accompanying caption text glows red and the sensor requires attention when a value enters the diagram’s inner region. The problem could be resolved by cleaning and calibrating the sensor, or the sensor might need to be replaced. No matter the manufacturer, the values associated with these diagnostics are the same for all Memosens pH sensors.
The only transmitters with the ability to extract this diagnostic data and display it in a clear graph are the Knick Stratos Multi, Protos, and Portavo 907 & 908 Transmitters.With the aid of these data, you may work out whether your sensor needs to be cleaned, calibrated, put back into operation, or changed. Here are a few things to think about when you notice a parameter value starting to decline. These recommendations, if properly implemented, will help to guarantee a sound and trustworthy measurement loop and to extend the useful life of your sensor.
Slope
The slope in the pH sensor diagram represents the change in mV potential from one pH unit to the next. A pH 7 environment or material should always register as 59.16mv at 25°C. This value will result in a 100% slope. When modified during calibration, the slope value should ideally remain within the range of 80–100%. If slope measurements routinely drop below 90%, operators should clean and calibrate their sensors. You should probably replace the sensor if you observe that the slope is frequently decreasing below 80%.
Zero Point
A steady zero point requires accurate calibrations. Changes in the sensor’s zero point typically point to reference system contamination. The zero point can be brought back to its ideal reading of +/-30 mv with the help of a thorough cleaning and recalibration of the sensor. This value will inevitably change over time. The drift rate may vary depending on the procedure. The sensor may have been polluted and has to be changed if the zero point continually deviates from the optimum reading.
Response Time
The sensor reaction time is a sign that the measured value has stabilised. Throughout the calibration procedure, the transmitter records reaction time. Less than 30 seconds is the optimal reaction time for a new Memosens pH sensor. The sensor’s response time may lengthen as it becomes older. Response time can be sped up with thorough cleaning, rehydration, and calibration. After cleaning and calibration, if response time rises, the sensor probably has to be replaced.
Cal Timer
This feature is a customisable diagnostic that is optional and user-driven. A calibration preference can be entered, and calibrations can be scheduled to occur periodically. However, it is advised that Cal Timer be turned off for a process that needs the sensor to work continuously in order to prevent interruptions. The sensor will stop working until it is calibrated at a predetermined interval once a calibration interval has been established. Cal Timer in the pH Sensor Diagram is a special sensor diagram tool that helps operators stay on schedule for procedures that require periodic calibrations.
Sensor Wear
The most obvious sign that a sensor might need to be replaced is this diagnosis. A weighted computed value of 0 to 100% represents sensor wear. The loads the sensor has experienced determine this. Extreme process conditions, such as high temperatures and corrosive process media, for instance, will result in accelerated wear. This value gives key information about the state of the sensor and enables operators to plan for when it needs to be replaced. After cleaning and calibration, if depletion still exists, it is likely that the sensor needs to be changed. Increased sensor lifetime can also be achieved by implementing automated retractable housing/cleaning systems.
Sensocheck/Glass Impedance
The impedance between the measurement and reference electrodes is tracked by this value on the sensor diagram. The value of impedance is dynamic and constantly varying. A sensor’s membrane can deteriorate when it is exposed to an extremely acidic or basic process. Additionally, a broken sensor could be indicated by this number, which would read as 0 impedance. It might also indicate that debris is beginning to build up on the sensor membrane. The membrane’s dehydration can also have an impact on impedance. It is crucial to properly position sensors in the process. Impedance is impacted by misalignment from the process media as well. Impedance is also impacted by membrane moisture. Make sure to keep your sensor correctly stored in the KCl (potassium chloride) solution-filled hydrating wetting cap.
Know Your Sensor and use the pH Sensor Diagram
To ensure accuracy and consistency, liquid analytical sensors must be maintained. Operators can identify which instrumentation component requires care with the aid of the sensor diagram feature included on the Knick Stratos Multi and Protos transmitters, as well as the Portavo 907 & 908 transmitters. View some of our useful videos on using diagnostics data to troubleshoot.
