Sensors & Transducers

Advanced pH sensor technology from Foxboro

June 2018 Sensors & Transducers

Foxboro has been manufacturing pH probes and transmitters for over seventy years. Using this field-proven experience, the company has now developed the Dolphin series of pH sensors.

Due to the advances in manufacturing techniques and the discovery of new materials, today’s pH sensor technology looks and operates differently. In pH probes of the past, the reference junction had to be kept wet at all times. In the latest Foxboro pH sensor technology incorporated in the Dolphin series, the entirely solid-state reference junction is manufactured from Nafion and Ceramic, which eliminates the need for wetted parts.

1. Double junction 
    reference tube using a Nafion Barrier. 
2. High temperature gel. 
3. RTD and solution assembly. 
4. Ceramic reference junction. 
5. Unique spherical or flat glass pH electrodes.
1. Double junction reference tube using a Nafion Barrier. 2. High temperature gel. 3. RTD and solution assembly. 4. Ceramic reference junction. 5. Unique spherical or flat glass pH electrodes.

The probes body is manufactured from PVDF (polyvinylidene fluoride, commercially known as Kynar), which incorporates the microprocessor-based smart electronics where all the sensor data and calibration curves are recorded and stored. The probe also has features built-in, temperature compensation and the digital signals from sensor to transmitter are less prone to RFI/EMI interference than conventional analog signals.

An added benefit of the Dolphin series is that users can connect the probes directly to a PC or laptop for ease of use. Via FDT and DTM certified software, the probes can be calibrated in the workshop prior to installation. In addition, information can also be extracted from the probe for maintenance and diagnostic purposes.

In summary, the advantages of the Dolphin series pH probes include:

• Unique Nafion ion barrier prevents reference junction fouling and reduces the need for cleaning.

• Rugged PVDF sensor body is chemical and abrasion resistant, resulting in longer service life.

• No metallic wetted parts, results in corrosion resistance and longer life in strong chemical solutions.

• Unique pH electrode formulations, both flat glass for abrasion resistance and domed glass for high-temperature service.

• Enhanced diagnostics reduce the amount of time required to assess sensor health.

• Unique sensor mounting design provides faster insertion and removal from the process.

• Kyner sensor body and a rugged electrode result in reduced breakage during handling.

For more information contact Johan van Jaarsveldt, EOH, +27 (0)87 803 9783,,


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