pH Sensors in Aggressive Chemical Applications: Unlocking Better Performance and Longevity

Aggressive and toxic chemicals pose significant challenges to measurement instruments in chemical processes. pH and ORP sensors with porous or open reference junctions often fail prematurely due to reference electrode poisoning. Applications containing chemicals such as cadmium, peroxide, cyanide, ammonia, chlorine, hydrogen sulfide, and radioactive materials are the main culprits.

These chemicals diffuse through the porous junction, a critical operational component of the sensor, and contaminate the Ag/AgCl reference electrode within. The resulting contamination inevitably leads to severe measurement performance issues or, worse, rapid sensor failure.

The Consequences of Premature Sensor Failure

When sensors fall short of their expected lifespan, the costs go beyond the financial burden of replacing them. The labor overhead for frequent recalibration and replacement is high. Managing spent sensors—potentially heavily contaminated with harmful materials—safely and legally is another major concern. Neglecting proper disposal protocols can lead to environmental damage and expose companies to financial risk.

Prolonging pH Probe Life: The Ion Trap Solution

When dealing with applications where sulfides or proteins are prevalent, a pH probe with a built-in ion trap can be a game-changer. The ion trap, in essence, acts as a shield, preventing Ag+ ions from infiltrating the reference electrolyte solutions and reacting with the process material to form insoluble precipitates. These precipitates can obstruct the porous junction, rendering the probe inoperative.

Non-Porous pH and ORP Sensors: The Ultimate Solution?

Another viable option to extend the pH probe lifespan in “difficult” applications is to use non-porous pH and ORP sensors. In contrast to a porous junction, these sensors employ an ionically conductive interface barrier to connect the process to the reference electrode. This barrier is designed to completely isolate the process liquid from the reference half-cell electrolyte, effectively eliminating the risk of internal contamination by the process material.

This design advantage allows non-porous sensors to perform reliably even in challenging applications—whether they contain toxic chemicals, biological agents, or even radioactive materials. And in terms of environmental responsibility, non-porous junction sensors are clear winners. With no internal contamination, they can be simply externally cleaned before disposal, mitigating the environmental impact.

Choosing the Right Sensor for Aggressive Applications

In conclusion, choosing the right pH sensor can significantly reduce maintenance time, improve measurement accuracy, and prolong pH probe lifespan in aggressive applications. pH sensors equipped with ion traps or non-porous reference junctions have been proven to perform better than other designs in aggressive applications.

However, it’s important to evaluate each application’s specific requirements and challenges to select the most appropriate pH sensor design. The sensor’s compatibility with the chemicals used, the level of maintenance required, and the associated disposal considerations are among the key factors to consider when making this critical choice.

Considering the complexity of dealing with aggressive chemical applications, exploring cutting-edge sensor technology can be a wise strategic move. It’s about choosing the solution that not only meets your immediate needs but also aligns with your long-term operational and environmental goals.

Time to Upgrade Your pH Sensors?

Are your current pH sensors not up to the task? Are you facing frequent failures, extensive maintenance, or disposal challenges? Now might be the right time to consider a switch to more advanced sensor technology. A choice that offers better performance, longer life, and easier disposal could be the key to improved efficiency and compliance with environmental standards. As an established supplier of measurement instrumentation, analyzers, and control products, we can help you find the best fit for your operation.

Contact us at South Fork Instruments today.

Read more:
How to clean pH electrodes for maximum life
Balancing pH levels in industrial wastewater treatment: A comprehensive guide
Analog vs. Digital Memosens Probes: What’s best for process analytics?

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