Capacitive Ceramic Pressure Sensors used in Ultrasonic Doppler Flowmeters
The application:
Ultrasonic Doppler flowmeters are widely used in industrial and environmental applications to reliably monitor the flow rate of fluids containing solid particles, such as wastewater, sludge, or river water. These devices are equipped with integrated ultrasonic sensors that emit and receive sound waves. The measurement principle is based on the Doppler effect: moving particles within the fluid alter the frequency of the reflected sound waves, enabling the calculation of flow velocity.
To determine the volumetric flow rate, the cross-sectional area of the liquid stream must be known, which depends on the hydrostatic pressure. However, pressure measurement can be challenging due to fluctuating temperatures, aggressive media, and pressure changes in the measurement environment.
By integrating capacitive ceramic pressure sensors into these ultrasonic Doppler flowmeters, pressure can be measured reliably and precisely. This enables accurate volumetric flow calculations, improves system control, and enhances operational safety.
The challenge:
- High temperature and corrosive environments
Liquids used in industrial processes often contain corrosive chemicals or are handled at elevated temperatures. These conditions can damage conventional pressure sensors. In chemical plants, for example, acidic or alkaline sludges can corrode metal-based sensors, leading to measurement deviations.
- Pressure fluctuations
Doppler flowmeters are frequently used in applications with pulsating flows. The resulting rapid pressure changes can stress sensitive sensor components and potentially cause failures.
- Electromagnetic interference
Industrial environments are often subject to strong electromagnetic influences, caused by motors or wireless communication systems. Sensors with insufficient electromagnetic shielding may produce noisy signals under these conditions, significantly reducing measurement accuracy.
Our solution:
Ceramic capacitive pressure sensors such as Ceracore USC30 from Endress+Hauser, constructed from high-purity ceramic (99.9% Al₂O₃), offer a robust solution for these operating environments thanks to their unique material properties and design. Their corrosion resistance, high-temperature stability, fast response time, and overload protection make them ideal for applications where traditional sensors reach their limits.
The chemically neutral membrane is perfectly suited for use in aggressive fluids. Unlike metal-based sensors, capacitive ceramic sensors remain unaffected by acids, alkalis, or saline solutions, ensuring long-term measurement accuracy even under harsh conditions.
With an outer diameter of 17.5 mm, these sensors also enable the development of compact flowmeters. This is particularly advantageous for portable Doppler flowmeters used in field measurements of river discharge or sewage flows.
Endress+Hauser Sensors&Components has been developing customer-specific sensors for over three decades and focus the activities on partnership-based collaboration with customers. An interdisciplinary team from development, product management and sales handle implementing the users’ requirements in the best viable way.
Detailed information about the portfolio of capacitive ceramic pressure sensors can be found on this product page.