Learn How a pH Sensor Works

pH Sensor (Mettler)

The video below will provide you with a basic visual understanding of the design of pH sensors and the principles behind pH probe operation. Before viewing the video, here are some pH basics:

What is pH measurement?

pH (potential of hydrogen) is a figure used to express the acidity or alkalinity of a solution on a logarithmic scale. On this scale 7 is neutral; lower values are more acidic and higher values are more alkaline, with a maximum measurement of 14. In process applications, pH is generally measured with an inline pH probe, the most common being the glass combination electrode. Additionally, an inline pH probe generally requires a process adaption, cable and transmitter.

How does a pH probe work?

A typical combination pH probe is made up of two separate electrodes built into one, a pH sensing electrode, and a reference electrode. In the simplest terms, a pH sensing electrode uses a special pH sensing glass membrane. H+ ions permeate the membrane creating a charge. The potential between the two electrodes is the measurement of hydrogen ions in the solution, giving the measure of pH. For more details, download the free pH Theory Guide.

What is the difference between a pH probe, a pH sensor and a pH electrode?

Absolutely nothing! The three terms are used interchangeably in the industry. They can be used for probes that are used in-process or in laboratory measurement. You may also hear the term "pH meter". This can be used for a piece of laboratory equipment, or the term pH meter can also be used to mean the combination of an inline pH probe, cable and transmitter.

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Comparison of Digital and Analog pH Sensors

The video, produced by Mettler Toledo, provides a comparison of digital and analog pH sensors, particularly focused on operational and calibration procedures used for each. The digital version provides some real time saving advantages. Share you process measurement and analytical challenges with a process analytics specialist. Leverage your own knowledge and experience with their product application expertise to develop the best solutions for your operation.

Automatic pH Sensor Cleaning and Calibration Saves Time and Cost

Automated pH sensor cleaning and calibration
with EasyClean 400
Courtesy Mettler Toledo

Measurement of pH is a common analytical operation in liquid processing. Whether chemical or wastewater operations, pH measurement provides useful information about process condition.

The sensors used for measuring pH can require care and maintenance, in the form of cleaning and calibration, to maintain peak performance. Traditionally, these operations have been performed manually by trained technicians. The task, though, is a good candidate for automation to provide cost savings and uniformity for sensor cleaning and calibration.

Mettler Toledo manufacturers four different automated cleaning and calibration systems for their analytical sensors. The offering ranges from simple water rinsing or compressed air cleaning to prevent build up to fully automated cleaning and calibration systems requiring little in the way of human intervention.

The technical data sheet below provides details about the fully automated system. Share your analytical measurement challenges and requirements with application specialists, combining your own process knowledge and experience with their product application expertise to develop effective solutions.

Automated pH Sensor Cleaning and Calibration from Alliance Technical Sales, Inc.

Improve Liquid Processing Performance With Sensor Technology

In the field of industrial processing, there is always a striving for improvement. Increasing output, improving output, and decreasing resource input are the watch phrases for process designers and operators in every industry.

Liquid processing often involves analytical instruments that produce periodic or continuous measurements of process conditions. The accuracy of these instruments will directly impact the quality and efficiency of the process, so great attention is paid to maintaining sensors and related instrumentation in top working order. Mettler Toledo, globally recognized leader in analytical sensor technology, provides a comprehensive solution for liquid analytical operations with its line of smart sensors and companion management software.

The ISM sensor technology couples the sensor with an onboard processor that continuously monitors sensor performance and delivers real time information about accuracy and time before maintenance. This empowers users to efficiently schedule maintenance tasks and operate with assurance that the data delivered by the sensor is reliable.

The video below sums up the ISM sensor benefits in under one minute. Share your process analytical challenges with application specialists and combine your process knowledge with their product application expertise to develop effective solutions.

New Dissolved Ozone Sensor

Mettler Toledo, under the Thornton brand, has released a dissolved ozone sensor employing the company's Intelligent Sensor Management technology that helps to streamline the use of sensors for measuring pH, conductivity, dissolved oxygen or ozone, and a host of other aspects of pure water. The pureO3 sensor technology provides rapid response in a sensor assembly with a built in digital measuring circuit and Intelligent Sensor Management (ISM®). The pureO3 is designed for monitoring low concentrations of dissolved ozone in semiconductor and pharmaceutical pure water samples, bottled water and similar applications. Minimal maintenance requirements and reliable long-term operation are hallmarks of this sensor.

How it works, in the company's own words...

"The pureO3 sensor uses a gas permeable membrane to separate the sample from the electrochemical cell inside. Ozone diffuses through the membrane in direct proportion to the partial pressure of ozone outside the sensor.The cathode and anode inside the sensor are polarized with a voltage to enable the electrochemical reaction of ozone. Ozone is reduced at the cathode while the anode is oxidized, producing a current in direct proportion to the amount of ozone present. The very low current developed by these sensors allows them to have a long life with low maintenance. An embedded temperature sensor enables temperature compensation to adjust for the changing permeability of
the membrane with temperature. In addition, the instrument uses the temperature value to convert the ozone partial pressure signal to a dissolved ozone concentration value by compensating for the changing solubility of ozone with temperature."

Benefits to the user from the ISM® based sensor.

• Full sensor identification by type and serial number.
• Calibration history with actual calibration, factory calibration, and last three calibration.
• Programmable timer to facilitate maintenance planning, reducing downtime.
• Starting calibration interval of 90 days.
• Time to maintenance function integrates ozone concentration over time, indicating replacement time for membrane body and electrolyte.
• Dynamic Lifetime Indicator for inner body used ozone concentration integration to predict life of inner body and membrane. Starting values, membrane body lifetime 180 days, inner body 1080 days.
• Sanitization counter allows the limit of ozone concentration and duration of sanitization cycleto be defined on the transmitter.

The pureO3 sensor with ISM operates with the M800 and M300 transmitters. ISM features enable users to maximize the lifetime of the sensors and minimize downtime by predicting when sensor maintenance is required. Contact a product application specialist for all the details. Share your process measurement challenges with experts, combining your process knowledge with their application expertise to develop the best solutions.

Deliver Incremental Productivity Boost With Intelligent Sensor Management

pH/ORP Probes
Mettler Toledo Ingold

It is almost a universal goal that we all must strive to increase productivity and efficiency. Whether factory floor, front office, warehouse, or any other facet of a business, saving time and delivering more output per unit of input is top of mind for business process operators.

Analytical measurement systems for chemical processing are included in the "business processes" mentioned above. Everything done for profit is a business process. Managing analytical instruments and systems for a fluid based process can be time consuming, as well as a significant cost center. There are modern instruments and components that can improve the effectiveness of analytical processes, reducing the recurring financial and manpower expense while improving the reliability and performance of the process.

Mettler Toledo, under their Ingold brand of analytical instruments, has developed their Intelligent Sensor Management (ISM) system to boost product quality and yield, while simultaneously reducing operating costs. The system makes optimum use of digital technology to bring some real user benefits.

• More precise measurement signal
• Advanced sensor diagnostics
• Predictive maintenance functions
• Rapid sensor change out

The white paper included below provides a clear overview of all that the ISM delivers and how it will save time and expense. Share your analytical challenges with a product specialist and combine your process expertise with their product application knowledge to produce effective solutions.

Intelligent Sensor Management From Ingold from Alliance Technical Sales, Inc.

Safeguarding CO2 Measurements: How Intelligent and Automatic Sensor Protection Increases Performance

Instrumentation uptime and accurate measurement values are core requirements of in-line dissolved CO2 measurement systems used in carbonated soft drink facilities, breweries and boutique beverage producers. The stability and protection of the wetted sensor along with the instrument air supply are core requirements to ensure reliable measurement data. Instrument damage, incorrect CO2 readings, and poor quality can result from an unknown or undetected failure of the sensor.

The following paper, courtesy of Mettler Toledo Ingold explains how intelligent and automatic sensor protection increases reliability, quality and performance.

Safeguarding CO2 Measurements: How Intelligent and Automatic Sensor Protection Increases Performance from Alliance Technical Sales, Inc.

For more information on CO2 measurement, contact:
Alliance Technical Sales, Inc.
312 Park Avenue Unit 145,

Clarendon Hills, 60514-0145
Phone: 630-321-9646
Fax: 630-321-9647
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