pH measurement is a critical process in various industries, from pharmaceuticals and food production to chemical manufacturing and wastewater treatment. Traditional pH probes function effectively under normal atmospheric conditions, but in specialized environments like partial vacuums, the challenges increase significantly. This is where polymeric reference junction pH probes, particularly those from REFEX, shine. We will get to the impact of REFEX pH probes and its polymeric reference junction technology later in this post.
First, let’s briefly explore the importance of pH probes in partial vacuum service and discuss the challenges these environments pose.
Understanding the Role of pH Probes in Partial Vacuum Environments
Partial vacuum environments—where the pressure is lower than atmospheric pressure—are common in many industrial processes. These environments are necessary for processes such as vacuum distillation, filtration, fermentation, and semiconductor manufacturing. Accurate pH monitoring is essential in these processes where it contributes to efficiency, safety, and product quality.
Industries that often require pH probes in partial vacuum conditions include:
- Pharmaceuticals: During processes like vacuum distillation and drying, maintaining precise pH levels is crucial.
- Chemical and Petrochemical Processing: Vacuum reactors are often used to control chemical reactions.
- Food and Beverage: Fermentation and vacuum packaging can involve low-pressure conditions.
- Semiconductor Manufacturing: Chemical cleaning and etching carried out under vacuum conditions requires strict pH control.
Challenges of Using pH Probes in Partial Vacuum Conditions
Operating pH probes in partial vacuum service is more complex than in standard atmospheric conditions. The reduced pressure creates a unique set of challenges for traditional probes, such as:
- Electrolyte Leaching: Most pH probes have a porous reference junction (typically ceramic or PTFE) and use a liquid or gel electrolyte. When exposed to partial vacuum, the reference cell electrolyte within tends to be “sucked” into the process. Then, when the process returns to normal pressure, its fluids will be “pushed’ through the reference junction into the probe, causing dilution of the electrolyte and potentially poisoning the reference electrode itself. This can lead to unstable readings and significantly shorten probe lifespan.
- Outgassing: Under vacuum, gasses dissolved in the process fluid may escape, creating bubbles that can cover the reference junction and interfere with the pH measurement.
Introducing REFEX and Polymeric Reference Junction Technology
To overcome these challenges, polymeric reference junction pH probes have emerged as a breakthrough technology. Designed specifically to withstand harsh environments like partial vacuums and aggressive media, polymeric junction probes offer superior performance by addressing issues that have always plagued conventional pH sensors.
REFEX, a leading provider of advanced pH/ORP probes, utilizes this innovative technology to ensure reliable pH measurements in demanding environments. At the heart of every REFEX electrode is a unique nonporous reference system that delivers high-quality performance, stable readings, and accurate measurements, making them ideal for partial vacuum applications.
Key Advantages of REFEX:
- No Liquid-Liquid Contact: Polymeric junction probes avoid the common issue of electrolyte loss under low pressure, making them ideal for use in partial vacuum conditions.
- Resistance to Fouling: Traditional probes often suffer from fouling/blockage of their porous reference junction by the process fluid. Probes using a non-porous polymeric reference junction do not have this issue, ensuring long-term consistent performance even in demanding applications.
- Outgassing-Resistant Design: The solid-state design ensures that the entire shaft of the probe is chemically active as the reference junction, so the probes’ entire surface area is in contact with the process. The attachment or gathering of bubbles formed by outgassing has no effect. By always remaining in contact with the process, the probe delivers reliable pH readings even in the presence of gas bubbles.
- They Work with Existing pH Analyzers and Transmitters: REFEX sensors connect directly to all of the top brands of [analog] pH analyzers and transmitters and have the same footprint as most popular sized probes. Upgrading an existing pH probe to take advantage of the benefits a REFEX probe offers is simple and straightforward.
Best Practices for Operating REFEX Polymeric Reference Junction pH Probes in Partial Vacuum Service
In addition to leveraging the superior design of polymeric reference junction probes, adopting best practices in installation, calibration, and maintenance is crucial for optimal performance in partial vacuum service:
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Routine Maintenance
Although REFEX probes are highly resistant to coatings and fouling, periodic cleaning is still recommended for optimal performance in “dirty” processes. Installation in a retractable housing allows for the probe to be cleaned periodically (either manually or automatically) to ensure continued service without the need to shut down the process or sample line. -
Temperature Compensation
Vacuum environments can cause sudden and extreme temperature changes. Using REFEX pH probes with built-in temperature compensation ensures that readings remain accurate even as temperatures fluctuate. -
Protective Housing Options
In particularly harsh processes, the use of a protective housing for a pH probe can extend its life. Housings shield the probe from direct exposure to the most extreme conditions, maintaining a more controlled measurement environment.
These practices help ensure that REFEX probes perform reliably and maintain accuracy over their extended lifespan, even under the challenging conditions of partial vacuum environments.
Final Word
pH monitoring in partial vacuum environments presents several challenges, but REFEX polymeric reference junction technology offers an innovative solution. By eliminating liquid electrolyte loss and dilution, durability against contamination, and rejection of bubble effects from outgassing, REFEX probes can deliver reliable and long-lasting performance in most partial vacuum applications.
With the right probe technology and best practices in place, industries like pharmaceuticals, chemical processing, and food and beverage production can achieve accurate, stable pH measurements in vacuum environments where other pH probes struggle. Investing in REFEX pH probes for partial vacuum service is a step toward greater reliability, reduced maintenance, and extended probe life in challenging conditions.
Contact South Fork Instruments
Ready to discuss how you can leverage REFEX? Contact us at South Fork Instruments by calling 925-461-5059 or filling out this form. Our state-of-the-art instrumentation products provide reliable, low maintenance, high-value results for plant control and quality improvement for a wide range of industry segments, including chemical plants, breweries, refineries, mining, power generation, food processing, offshore/onshore oil production, and pipelines.
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