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Master hydrofluoric acid safely

HF concentration measurement that accepts no compromises. Neither in materials nor in accuracy.

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Real-time measurement

Continuous monitoring without delay

Maintenance-free

No moving parts or wear components

Maximum accuracy

Precise measurement even under difficult conditions

Reduced operating costs

Cost-efficient solution with a short payback period

Hydrofluoric acid (HF) is the aqueous solution of hydrogen fluoride and holds a unique position in chemistry: Although it is considered a moderately strong acid, its extreme toxicity and ability to dissolve glass and silicate materials make it one of the most dangerous industrial chemicals of all. At the same time, hydrofluoric acid is indispensable in certain key industries, for example in semiconductor production, petrochemical alkylation units, or metal treatment. Precise monitoring of HF concentration is not optional, but a prerequisite for process safety, product quality, and plant protection. LiquiSonic® was developed for these requirements, with special coatings and a measuring principle that withstand hydrofluoric acid.

  • HF attacks glass, quartz, and silicates - conventional sensors and electrodes are unusable!
  • Even small amounts pose an acute danger to life - manual sampling is a safety risk!
  • The concentration changes during the process - without measurement, no stable process is possible!

Concentration measurement with LiquiSonic®
 

LiquiSonic® was developed, among other things, for safe use in hydrofluoric acid processes. All wetted parts are optionally made of PFA, ETFE, or other HF-resistant materials. Standard materials that would not withstand the acid are not used.

For example, in petrochemical alkylation units, the system simultaneously measures HF concentration, water content, and ASO content, the three critical parameters for process control and safety. Predefinable limit values ensure that the system immediately triggers an alarm in the event of critical deviations. In addition, LiquiSonic® can be seamlessly integrated into existing process control systems.

Our measuring system operates continuously and fully automatically. This means manual sampling is eliminated completely. At the same time, the precise concentration data enable targeted, demand-based dosing of hydrofluoric acid, which noticeably reduces consumption and operating costs.

Typical challenges

  • Extreme material corrosivity – standard materials fail
  • Toxizität & Personalschutz – manuelle Probenahme hochriskant
  • Concentration drift – composition changes regularly
  • Safety-critical reactions – e.g. acid runaway
  • Leakage risk – potential HF ingress into secondary circuits

Our solution

  • All wetted components made of HF-resistant materials
  • Fully automatic inline measurement
  • Continuous real-time measurement
  • Definable limit values and direct integration into process control systems
  • Even the smallest concentration changes are detected

Application examples

Hydrofluoric acid is indispensable in some of the world's most demanding industrial processes. That is exactly what makes precise monitoring critical. In petrochemical alkylation units, HF acts as a catalyst in the production of high-octane fuels; even small changes in water content can lead to uncontrollable acid reactions. In semiconductor manufacturing, the exact HF concentration in the etching bath determines the quality of every single wafer. And wherever HF is conveyed through pipelines and heat exchangers, an undetected leak in the secondary circuit can cause serious damage within a short time. What all these applications have in common: Precise monitoring of HF concentration is not optional, but a prerequisite for process safety, product quality, and plant protection.

Semiconductor industry

HF is the standard etchant for SiO₂ layers on silicon wafers. Wet-chemical cleaning and etching processes (wafer cleaning, BOE solutions) are unthinkable without HF.

Petrochemical alkylation

HF serves as a catalyst in alkylation units for producing high-octane fuels (isoalkylates) from butane and olefins.

Surface treatment

Matting, engraving, and cleaning of glass, crystal, and quartz. Also surface treatment of titanium, tantalum, and other specialty metals.

Fluoride production

Precursor for sodium fluoride, aluminum fluoride, fluorspar derivatives, and fluorinated polymers (PTFE precursors).

Solar industry

Etching and cleaning of silicon surfaces in photovoltaic production.

Over 35 years of experience in concentration measurement

SensoTech has been a leading provider of inline measurement technology since 1990 and has established itself as a specialist in precise concentration and density measurements.

Our systems are used worldwide, including in critical applications.

35+

Years of experience

1000+

Installed systems

50+

Countries worldwide

ISO 9001

Certified quality

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Frequently asked questions

What effects do concentration fluctuations have in HF process baths?

Concentration drift is unavoidable in HF processes. The key is to detect it in real time and counteract it in a targeted manner. LiquiSonic® continuously measures the bath concentration and outputs an up-to-date measured value every second. Deviations from the target value are immediately visible, and replenishment processes can be controlled in a targeted and demand-based manner.

What role does continuous process monitoring play in the prevention of acid runaways?

An acid runaway occurs, for example, when the water content in the HF catalyst phase rises uncontrollably. LiquiSonic® in this case monitors the HF concentration, water content, and ASO content simultaneously and continuously. Defined threshold values trigger an alarm as critical ranges are approached, before an uncontrolled reaction can begin. The system can be integrated directly into existing process control systems.

For which HF concentrations and process conditions is LiquiSonic® designed?

LiquiSonic® covers the entire industrially relevant concentration range. From dilute HF solutions in the single-digit percentage range, as used in semiconductor manufacturing, to concentrated HF streams in petrochemical alkylation plants. Measuring ranges, temperature limits, and pressure resistance are configured specifically for the application.

Can LiquiSonic® measure multiple components simultaneously?

Yes, for example in alkylation plants, LiquiSonic measures® the HF concentration, water content, and ASO content simultaneously, the three critical parameters for process control and safety. For other applications, the measurement scope is configured according to the process requirements.

How accurately does LiquiSonic® measure?

The system achieves accuracies of up to ±0.05 wt% in concentration measurement. The integrated temperature compensation ensures that measured values remain reliable even with fluctuating process temperatures.

Can LiquiSonic® be integrated into existing safety and control systems?

Yes. LiquiSonic® unterstützt gängige Industriestandards wie 4–20 mA, Profibus und Modbus und lässt sich damit in nahezu jede bestehende Prozessleittechnik integrieren. Grenzwerte können frei definiert werden. Bei Überschreitung wird, falls gewünscht, Alarm ausgelöst und eine Notabschaltung eingeleitet.

How complex is the commissioning of the HF concentration measurement system?

The sensor is usually installed directly in the process line and can generally be put into operation quickly. SensoTech provides application-specific presettings and, if required, support from experienced service personnel.

How high is the maintenance effort during ongoing operation?

LiquiSonic® operates without moving parts and without consumables. Under normal operation, no intervention is required. This noticeably reduces operating costs and eliminates downtime caused by sensor replacement.

How can safe process monitoring be implemented in HF concentration measurement?

LiquiSonic® measures fully automatically and continuously directly in the process. Manual sampling is no longer required. The measured values are available in the control system at all times, ensuring complete process visibility without operating personnel having to come into contact with the acid.

How can hydrofluoric acid be prevented from entering secondary circuits?

Even the smallest HF ingress into secondary circuits can have serious consequences. The measurement technology used must therefore be capable of detecting minimal concentration changes quickly and reliably. LiquiSonic® reliably detects changes in acid concentration and automatically triggers a signal when defined threshold values are exceeded.

What requirements must measurement systems meet in order to determine HF concentration reliably?

Conventional sensors fail with hydrofluoric acid because their materials cannot withstand the acid. LiquiSonic® was developed from the ground up for use in various media and is always customized to the respective application. In HF concentration measurement, all wetted parts are made of PFA, ETFE, or comparable HF-resistant materials. Further adaptations are possible according to customer requirements!

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