In many applications, the noninvasive control of liquid level in reservoirs like canisters is essential to guarantee proper function and application of a system. An appropriate technology here is the use of ultrasonic waves with their ability to pass layers like vessel walls and nontransparent, conductive and non-conductive materials.
- Evaluation Board Level Measurement
SonoQ’s easy to integrate module offers the possibility to add an ultrasonic level measurement to an existing system or to simplify the design of new products.
There are two different operation modes:
There is no need to use the existing serial interface. The module may be configured with the Evaluation Board or may be provided with the application specific parameters from SonoQ. The on-board open collector output raises a signal at defined liquid level (with defined hysteresis).
If the modules SPI interface is used, all parameter settings and read out of current liquid level are available for customers control unit.
There are three components available:
- Standard or application specific ultrasonic transducers
- Dry-coupling version for easy container removal
- Low-cost glue-on version
- Customized transducers
- Evaluation Board for quick putting into operation and configuration
- Level PCB
The non-invasive control of liquid levels is essential for many applications assuring proper functionality of components and systems. The ability of ultrasound to propagate through solids and liquids provides an almost ideal technology to implement this task. A preferred implementation for liquid level metering (LLM) attaches an ultrasound transducer to the bottom of the wall of the liquid container. A short ultrasound wave is transmitted from the transducer passing the container wall and travels through the liquid to the liquid air interface. This interface acts as an ideal reflector returning the ultrasound wave back to the transducer, where the time of arrival is registered or time of flight is estimated via ultrasonic signal processing. An increased delay of the arriving signals indicates a higher level, a reduced time of arrival a lower level. However, level metering requires the speed of sound in the fluid to be known. This knowledge is either obtained by calibrating or by measuring separately this parameter.
Besides propagating through container walls and hereby conveniently accessing the fluid for LLM, another main advantage of ultrasound is detecting foam fluid interfaces.
An appropriate technology here is the use of ultrasonic waves with their ability to pass layers like vessel walls and nontransparent, conductive and non-conductive materials. The usual method here is the echo sonography, where an ultrasound transducer produces a sonic wave which passes the liquid up to the liquid/air interface on top of the liquid where most of the wave will be reflected back. This wave is again received by the transducer. By estimation of the speed of sound inside the liquid and measuring the travel time of the bouncing ultrasound wave, the liquid level may be calculated.
One of the main advantages of the used ultrasound technology beside the non-contact measurement through the containers wall is the detection of foam/liquid boundaries.
Often the ultrasonic altimeter is - even though best applicable - not used because there is a need of certain knowledge about ultrasound signal processing and ultrasonic transducers.
Despite ultrasound is highly suitable for LLV it is often not utilized due to a lack of knowledge of ultrasound transducers and signal processing.
However, SonoQ’s easy to integrate module offers the possibility to add an ultrasonic level measurement into an existing system or to simplify the design of new products.
The PCB operates in two different modes:
The module is configured with the Evaluation Board or application specific parameters are provided by SonoQ. The on-board Open Collector output raises a signal at specified liquid levels (with defined hysteresis).
If the modules SPI-interface is used, all parameter settings and read out of actual liquid level are available for customers control unit.
- Level transducer
To measure with ultrasonic through a wall, a special design of the sensor is needed to mount the transducer on the wall material. With the unique contact material from SonoQ it is easy to mount the transducer on outside of the wall. The SonoQ transducer design considers for different opening angles and working frequencies:
- The type of coupling as immersion (highest performance)
- Dry coupling (easy handling if canisters are changed, but limited detectable level minimum) or glued-on
For standard application there are two types of transducer available from stock:
- 2 MHz with 10mm aperture and dry coupling (SQ-A1)
- 2 MHz with 10mm aperture and tape fixation (SQ-G1)
Because the transducer plays an important role to the quality of the level meter, generally application specific designs are possible. In that case, please contact the distributor or manufacturer for further consulting.
- Data Sheet
User Manual for the Evaluation Board for non-contact measurement with transducer
OEM PCB for non-contact ultrasonic level measurement
3.3V SPI - Version
Transducer 2 MHz with 10mm aperture
Transducer 2 MHz with 10mm aperture
tape fixation version