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Model 372 HF Resistant pH Sensor
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- ENHANCED RESISTANCE TO PROCESS ATTACK provided by field-proven pH glass formulation.
- EXTENDED SENSOR LIFE provided by double junction reference cell for process solutions that contain poisoning ions.
- MULTIPLE MOUNTING OPTIONS are accommodated by one-piece construction with process threads in two places.
- SUPERIOR CHEMICAL RESISTANCE due to rugged Ultem¹ body, completely sealed to eliminate sensor leakage.
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FEATURES AND APPLICATIONS
PH measurement has historically been conducted using thin glass membrane electrodes that slowly dissolve in water,
creating a pH sensitive surface layer. Some chemicals and/or conditions accelerate this dissolution process, causing
the electrodes to become very fragile and prone to breakage. Examples include high temperatures, caustic
exposure, steam exposure, and exposure to hydrofluoric acid. Hydrofluoric acid (HF) is commonly used to etch glass
and chemically attacks the silicon-oxygen bonds that hold the glass matrix together.
Rosemount Analytical's new Model 372 sensor uses a new glass formulation that slows down this attack considerably, making measurements in up
to 1% (10,000 ppm) HF cost effective and economical.
The presence of hydrofluoric acid in an application is affected by the pH. When the pH is high, nearly all the fluoride
ion will be present in the relatively benign free F- form. Lower pH values will convert the free fluoride to HF and
present a much harsher solution to measure.
The Rosemount Analytical Model 372 is an easy to install combination sensor that enables pH measurement of solutions
containing HF. Although sensor lifetime will differ based on the temperature, pH, and HF exposure, it will last
much longer than conventional glass electrodes.
SENSOR FEATURES:
- Cross linked polymer reference system is resistant to heat, solvents, acids, and most other chemicals
- Reference holds an excess of KCl, assuring saturation at all temperatures and extending in situ sensor life
- The Fluoride and Acid Resistant pH Glass formulation reduces the buildup of fluoride precipitates on the surface,
minimizing cleaning and calibration requirements.
- Glass Composition reduces HF attack by more than a factor of ten.
¹ Ultem is polyetherimide
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