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Orp Measurement Basics For The Process Industry

The ability of a medium to oxidise or reduce another medium is measured by its “oxidation-reduction potential,” or ORP.

When an oxidizer takes an electron from another molecule, it is said to be oxidising, and when a reducer gives an electron to another molecule, it is said to be reducing. A single mV value, which can be positive or negative, can be monitored by an ORP sensor to identify whether oxidation or reduction is taking place. The mV value is positive when a medium is oxidising. The mV reading will be negative when it is displaying reduction. Additionally, an ORP measurement known as “Redox” is frequently used. Reduction and oxidation are combined to form the word redox.

Creating ORP Sensors

Both an ORP electrode and a reference electrode are parts of an ORP sensor. When considering the design of an ORP sensor, the transfer of electrons is crucial. Platinum, which is frequently used in ORP electrode fabrication, has low resistance. The electrode is able to exchange electrons with both oxidizers and reducers. Until a potential is formed, the electrode will continue to take or release electrons. After then, it produces millivolts. The reference electrode in an ORP sensor is commonly constructed of Ag/AgCl and submerged in a KCl reference substance, making it very similar to a pH reference electrode.

Using the ORP Measurement to Interpret

Chemical media that act as oxidizers or reducers come in a wide variety. Instead of receiving a precise indication of the chemical you are measuring when monitoring ORP, you instead receive a signal that an oxidizer or reducer is present. For instance, ORP sensors are frequently used in Pulp and Paper mills to regulate the injection of chlorine, which is employed as a disinfectant in the mill. A measurement of ORP is one that can only be inferred. However, when done appropriately and in conjunction with knowledge of the process medium being studied, ORP measurements can be a useful tool for detecting specific compounds in a processing environment.

Summary 

In process applications across many sectors where managing chemical compositions is crucial, we deploy ORP sensors. You may control the process in an effective and efficient manner by grasping the fundamentals of ORP measures.

5 Benefits Of Automated Systems

Many process settings make it challenging for operators to carry out all the maintenance required to maintain measurement accuracy and sensor health when using sensors in industrial processes. In these difficult applications, automated methods are intended to assist in addressing sensor performance concerns.

Operators have a variety of adjustable options to fit the requirements of their particular processes. Here are five advantages that automated systems can provide to operators and their operations:

Optimize Process Management

Based on the requirements of their process, operators can set up various diagnostics and sensor care choices when employing automated systems. Additionally, without removing the sensor from the process manually, the system can automatically retract, clean, and calibrate the sensor. By incorporating this, downtime is significantly decreased and process yield is increased.

 Maximize Process Uptime

Operators were forced to manually maintain their sensors before automation. However, this led to safety issues and significant process downtime for applications employing aggressive process media in frequently hazardous areas. The amount of downtime for these processes is significantly reduced by technicians by automating cleaning, retraction, and calibration. This eliminates the need for manual intervention, maximising user safety and process yield. Due to the precise nature of the programmable intervals in which these procedures are conducted, automated cleaning and calibration systems also significantly increase the lifespan of sensors.

Secure and Sterile Operation

By eliminating the requirement for routine manual manipulation of the sensor, automated solutions offer an extra level of confidence about process sterilisation. Automated systems are a convenient and safe way to reduce hazards in procedures where exposure to humans or elements could have a detrimental impact. In earlier installations, manual operation frequently necessitated leaving the process line open in order to extract or otherwise handle the sensor. It is not necessary for the process line to be open when using automated systems. The sensor will be safely retained in the process thanks to the automatic retractable holder’s secure latching, which also reduces the likelihood of misalignment or unintentional removal from the process.

Significantly Reduce Maintenance Costs

Traditional systems may require frequent and unnecessary maintenance. Operators have a greater grasp of the sensor’s status thanks to real-time diagnostic features and automated cleaning. Process-specific calibrations and programmable cleaning intervals support the maintenance of sensor performance over longer time periods.

Support User Safety

For applications where in-line measurements are taken in risky or otherwise difficult-to-reach regions, automated solutions provide a dependable and secure approach to promote operational safety. Automation lowers risk by doing away with the requirement that an operator be present in person during retraction, calibration, and cleaning. For instance, from a control room, workers can securely change cleaning and calibration intervals without stopping their process.

Still interested in learning how automated technologies might improve your procedure? See which system M4 Knick’s automation portfolio offers for more details on which one best meets your requirements.

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.

Ph Monitoring In Semiconductor Chemical Clarifiers

pH Measurements on Semiconductor Wastewater Streams

In various stages of water treatment applications, the removal of hazardous substances depends on chemical clarifiers. Clarifiers are settling tanks created for use along semiconductor wastewater streams at various stages. To balance the low pH influent from the semiconducting production areas, lime is added. To ensure that pollutants are properly eliminated during the influent, clarity, and effluent stages of water treatment, pH monitoring is essential. The pH level in the clarifying system must therefore be checked and often regulated. Lime is used to the clarifying procedure to assist maintain ideal pH levels. But if not properly cleaned, over time, this lime can lead to buildup and possibly harm the pH sensor.

The Challenge of Semiconductor Chemical Clarifiers

When lime is introduced gradually over time and the overall chemistry of the chemical clarifier’s contents combine, a hazardous environment for the sensor may result. Users are hence required to do routine physical upkeep and cleaning. Failure to maintain cleanliness and upkeep can shorten the life of a sensor and cause incorrect readings from accumulation. This necessitates regular sensor changes, which raises costs and could shut down a process.

The Solution

Strong pH sensors are needed in semiconductor chemical clarifiers to survive both lime accumulation and the acidic environment. Due to the dual open connections in the Knick SE 554, the design offers a strong resistance to accumulation. Furthermore, the polymerized KCL offers resistance to leaching, and the proprietary Silamid reference reduces the rate of reference system poisoning. The glass used in the SE 554 can survive traces of hydrofluoric acid (HF). This extends the sensor’s lifespan for applications like clarifiers that process semi-conductor trash.

The CL-90 automated cleaning system and ARD 75 retractable immersion holder are used in conjunction with the Knick SE 554. The sensor is regularly maintained via automated cleaning cycles. The automated retraction and maintenance cycle reduces excessive buildup on the sensor, hence extending sensor life.

The CL-90’s transmitter, the Stratos Multi, is Memosens compatible. Memosens sensors, such as the SE 554, automatically provide the transmitter with calibration and sensor health data. Without any additional programming, the machine is ready to measure. Additionally, the Stratos Multi provides operators with diagnostics data that may be accessed instantly or via a DCS system.

What was the Customer’s ROI?

Reduced Downtime:The CL-90 and Knick ARD 75 retractable holders automatically clean the sensor to minimise drift and accumulation, which significantly reduces process downtime and unforeseen maintenance.