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Glycol and glycol-based media

Continuous concentration measurement of glycol-based media directly in the process: From classic glycol-water mixtures to specialty glycols and polyalkylene glycols.

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Real-time measurement

Continuous monitoring without delay

Maintenance-free

No moving parts or wear components

Highest accuracy

Precise measurement even under difficult conditions

Reduced operating costs

Cost-efficient solution with short payback time

Glycol-water mixtures are used, for example, in cooling circuits, heat transfer systems, and deicing processes to ensure frost protection, heat transfer, and process reliability. The correct concentration is crucial: if the glycol content is too low, frost protection decreases. If it is too high, chemical consumption and operating costs increase.

With LiquiSonic® SensoTech continuously measures the concentration of glycol mixtures directly in the process. The measurement is based on the speed of sound in the medium and the process temperature. This provides current concentration values without manual sampling and allows them to be used for monitoring, dosing, or process control.

Concentration measurement with LiquiSonic®
 

LiquiSonic® continuously measures the concentration of glycol and glycol-based media directly in the process, for example in a pipeline, in the bypass, or in the tank. The measurement is based on the speed of sound in the medium: an ultrasonic signal is sent through the liquid, the signal transit time is recorded, and the absolute speed of sound is calculated from it.

Since the speed of sound changes depending on the composition of the liquid, the concentration of the glycol-water mixture or a glycol-based process medium can be determined from it. In addition, the sensor measures the process temperature directly at the measuring point. This is crucial because temperature changes affect the speed of sound. Thanks to temperature compensation, the system provides stable and reproducible measured values even under fluctuating process conditions. All measured values are available in real time.

For glycol applications, this means that changes in concentration can be detected immediately. The measured value can be used for monitoring, quality assurance, or automatic process control, for example for targeted dilution, post-dosing, media changes, or recirculation of glycol streams. This eliminates dependence on sampling and delayed laboratory analysis. Another advantage: the measurement method is independent of the color, transparency, and conductivity of the liquid. This makes LiquiSonic® also suitable for applications where optical measurement methods or conductivity-based methods reach their limits.

Relevance of continuous glycol concentration measurement

Continuous monitoring of glycol concentration is crucial to reliably avoid both underdosing and overdosing. A concentration that is too low can, for example, impair frost protection in deicing processes or cause plant downtime, while a concentration that is too high results in unnecessary chemical consumption and higher operating costs. Manual sampling often provides only delayed snapshots and requires additional personnel effort. Especially in the case of fluctuating temperatures, media changes, or dilutions, continuous, inline, and temperature-compensated concentration determination ensures greater process reliability.

Benefits of continuous glycol concentration measurement

  • Continuous measurement instead of manual spot checks
  • Direct process integration
  • Fast response to concentration changes
  • Maintenance-free measuring principle without moving parts
  • Independent of color and transparency
  • Suitable for automated dosing and control processes

Application examples and measurement expertise

Depending on the application, the chemical structure, viscosity, water content, temperature range, and process environment of glycol mixtures differ significantly. SensoTech has already measured various glycol-based media with LiquiSonic® - from simple glycol-water mixtures to specialty media in chemical and refrigeration processes.

Application examples
Cooling circuits and heat transfer fluids
  • Industrial cooling circuits
  • HVAC / building services
  • Machine and plant cooling
  • Test benches
  • Heat transfer circuits
  • Data centers

Application examples
Aircraft deicing / deicing fluids
  • Monitoring of collection basins or return flows
  • Recycling or wastewater treatment
  • Avoidance of overdosing
  • Reliable compliance with the defined concentration range

Application examples
Process water, recovery, and wastewater
  • Determine residual concentration
  • Recovery potential
  • Disposal or treatment of glycol mixtures
  • Controlled post-dosing

 

Measurement expertise for glycol and glycol-based specialty media

With LiquiSonic® can also be used to monitor complex glycol-based media and specialty chemicals inline. The key factor is the relationship between speed of sound, temperature, and concentration in the respective medium. Based on application-specific calibrations, concentration changes can be continuously detected directly in the process.

Among the media already successfully measured are ethylene glycol, neopentyl glycol, di(propylene glycol) dimethyl ether, and polyalkylene glycol:

 

Ethylene glycol

Ethylene glycol-water mixtures are often used when frost protection, heat transfer, or deicing must be monitored. The concentration determines whether the desired frost protection is achieved and whether the medium is dosed economically.

  • Deicing fluids
  • Cooling circuits
  • Heat transfer fluids
  • Frost protection monitoring
  • Glycol recovery

Neopentyl glycol

Neopentyl glycol is a specialty glycol and an important raw material for chemical syntheses, including polyester resins, alkyd resins, polyurethanes, coatings, lubricants, additives, and plasticizers. For such media, robust inline measurement is particularly relevant, as concentration, purity, and process progress should be monitored continuously.

  • Chemical synthesis
  • Resin production
  • Polyester / alkyd resin processes
  • Quality control
  • Process monitoring for specialty chemicals

Di(propylene glycol)-
dimethyl ether

Solvents related to glycol and glycol ethers can also present relevant measurement tasks for inline analysis. Di(propylene glycol) dimethyl ether belongs to the glycol ethers and is used as a solvent. For such media, inline measurement can help monitor concentration changes, mixing ratios, or product quality directly in the process.

  • Solvent processes
  • Specialty chemistry
  • Coating and formulation processes
  • Quality control
  • Monitoring of mixing or treatment processes

Polyalkylene glycols

Polyalkylene glycols (PAG) are used, among other things, as synthetic oils or lubricants in technical applications. In the context of oil-refrigerant mixtures, LiquiSonic® OCR is already used in a wide range of applications.

  • Refrigerant / oil mixtures
  • Compressor test benches
  • Vehicle air conditioning
  • Building air conditioning
  • Research and test facilities

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 for 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

Why should glycol concentration be monitored continuously?

Continuous monitoring of the glycol concentration ensures that the medium remains permanently within the defined target range. A glycol concentration that is too low can increase the risk of plant downtime. A concentration that is too high, on the other hand, leads to unnecessary chemical consumption and higher operating costs. Inline measurement enables permanent monitoring directly in the process and helps detect deviations at an early stage.

How can glycol concentration be measured inline?

The glycol concentration can be measured directly in the pipeline or process stream with the LiquiSonic® measurement system. LiquiSonic® uses the speed of sound in the medium, which changes depending on concentration and temperature. The glycol concentration is continuously calculated from these measured values. This provides current process data in real time without the need to take manual samples.

What are the advantages of inline measurement?

An inline measurement provides continuous measured values directly from the process, while manual sampling only represents selective snapshots. This allows concentration fluctuations to be detected more quickly and processes to be controlled more precisely. At the same time, personnel effort and delayed results are reduced. Especially in dynamic processes, fluctuating temperatures, or changing media, continuous glycol concentration measurement increases process reliability and supports economical plant operation.

Can LiquiSonic® measure ethylene glycol, propylene glycol, and other specialty glycols?

Yes, LiquiSonic® can be used for various glycol-containing media, including ethylene glycol, propylene glycol, and special glycols such as neopentyl glycol. The measurement solution is designed and calibrated specifically for the application, the respective medium, the concentration range, and the process conditions. Glycol-based mixtures with additives, inhibitors, or other components can also be tested and calibrated accordingly if required.

Can frost protection or the freezing point also be determined from the glycol concentration?

Yes, for known glycol-water mixtures, frost protection or the freezing point can also be derived from the measured glycol concentration. The prerequisite is that the corresponding medium composition and concentration curve are known or calibrated. This enables the measurement system to help reliably maintain the required frost protection and detect underdosing at an early stage. This is particularly relevant for cooling circuits, heat transfer fluids, and de-icing applications.

Is the temperature automatically compensated during measurement?

Yes, the temperature is taken into account during concentration measurement. This is important because the physical properties of glycol-water mixtures change with temperature. Without temperature compensation, measured values could be distorted, especially in the case of fluctuating process or ambient temperatures. LiquiSonic® records the temperature directly in the process and uses it to calculate the concentration. This enables stable and reliable concentration measurement.

Is measurement also possible with colored, turbid, or additive-containing liquids?

Yes, inline measurement with LiquiSonic® is also suitable for colored, turbid, or additive-containing glycol-based liquids. Since the measurement principle is based on the speed of sound, the measurement does not depend on optical properties such as color or transparency. This is a clear advantage over optical methods, especially for process media with inhibitors, dyes, impurities, or changing composition.

Where is the LiquiSonic® sensor installed and can it be retrofitted into existing systems?

The LiquiSonic® sensor is installed directly in the pipeline, the process stream, or a suitable bypass. The optimal installation position depends on the respective system, the medium, the flow, and the process conditions. Retrofitting into existing systems is possible in most cases. This means that continuous glycol concentration measurement can also be integrated into existing processes without fundamentally changing the system concept.

Can the measurement be used for automatic dosing control or process control?

Yes, the continuously measured glycol concentration can be used to monitor, control, and regulate dosing processes. In the event of deviations from the defined target range, the dosing can be adjusted to avoid underdosing or overdosing. This allows chemical consumption and process stability to be better controlled. The measured values can be integrated into process control and used for automated concentration regulation.

How maintenance-intensive is the LiquiSonic® measurement system and is the sensor suitable for demanding media?

LiquiSonic® is designed for continuous industrial use and operates directly in the process without moving parts. As a result, the measurement system is maintenance-free and suitable for continuous measurement tasks in demanding applications. Depending on the medium, temperature, pressure, and chemical load, the sensor is selected to match the application. A suitable version can also be assessed and designed specifically for aggressive or special process media.

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