
Why ultrasonic systems matter for wastewater
Analog electronics served as the foundation for early ultrasonic systems.
They required a complicated setup and lacked dependability outside of the most straightforward uses.
The main problem was “false echoes,” which occurred when the “real echo” was obstructed and overpowered by signals from hard objects surrounding the measuring sound, such as stanchions, struts, or stirrers.
Today’s industry demands more from ultrasonic measurement equipment than only level sensors, including asset management, predictive maintenance, total expenditure (TOTEX) and event duration management.
These days, average ultrasonic systems are more than just sensors.
They are small pump station controllers.
A piezoelectric crystal is excited in an ultrasound system to produce an ultrasonic pulse.
The sound ‘echoes’ back off of objects, which reawakens the crystal.
The distance of the reflecting object affects how long it takes for the signal to return.
Technology advancements enable the real echo to be distinguished from echoes from fixed objects in the sound path.
There aren’t many situations in which this technology won’t function.
This device has no moving parts because it is non-contact, hence it requires no upkeep.
Nearly all wet wells have non-contact ultrasonic equipment installed.
The only function isn’t only level measurement.
Additionally, they are utilized for volume measurements, differential and pump control.
There are likely to be some myths and rumors floating about when a technology has been around for as long as ultrasonic systems have.
Most recently, it has been discovered that radar measurement is preferable to ultrasonic measurement.
While radar does have its uses and benefits in some circumstances, the development of digital data processing, low voltage and high acoustic power output in ultrasonic transducers has made it possible to solve about 95% of all applications.
A rough and foamy surface can reliably return a signal to an ultrasonic with high acoustic power.
What are the benefits of ultrasonic systems?
The technology is a well-established, well-understood measurement method that is regularly and reliably applied across a variety of businesses around the world.
Ultrasonic measurement is dependable and consistently produces correct measurements.
A number of standard control procedures give consumers a good level of control in addition to uniformity.
Customers are demanding more specialised solutions to their measurement needs in today’s diverse market.
Businesses are frequently reminded to cut back on their energy use and to keep their carbon footprint in mind.
To address those problems, low-power operational ultrasonic systems that are loop- or battery-powered have been created.
These devices offer solutions for tracking levels in far-off places and cutting down on-site power usage.
The battery life of these systems is measured in years thanks to developments in power management technology, which was previously not possible with non-contacting devices.
A non-contacting system performs admirably by sending a signal and listening for the return echo to determine distance.
Ultrasonic measurement, however, is still the cornerstone of process control and measurement today despite millions of dollars in research and development, tens of thousands of installations, and technological advancements.
What is radar?
Non-contacting radar technology comes in two types: pulsed and Frequency Modulated Continuous Wave (FMCW).
Both technologies emit radio frequency energy and measure the time it takes for a signal to return from a target with a higher dielectric constant than air.

The key difference between the two types of radar measurement is that pulsed radar emits a series of radio frequency pulses and measures the time it takes for the signal to return from the target to the emitter.
A challenge when at the speed of light is that the signal will return in a fraction of a microsecond.
At the same time, FMCW measures times of flight but transmits continuously, and constantly, varying the signal frequency.
The frequency of the returning signal is compared to the signal emitted at that moment using a mathematical technique called Fast Fourier Transform (FFT).
The difference between the two corresponds to the time the signal has taken to return.
FMCW is said to be the more accurate of the two because of its narrower beam angle and, in most cases, a stronger signal.
How are radar and ultrasonic systems different?
The control and measuring capabilities of radar and ultrasonic devices are identical.
The only significant factor in selecting the appropriate technology is the type of measurement.
Even in the crowded, cluttered wet wells, we see in routine sewage treatment applications, users can begin by assuming that ultrasonic measurement will solve their problem.
The dielectric constant of the reflecting item influences the strength of the radar echo as well.
There will be some measurement issues if the object being measured has a low dielectric constant and the barriers have a high dielectric constant.
Ultrasonic technology solely cares about an object’s surface texture and how well it can reflect sound, not how it was produced.
When should radar technology be considered?
Longer range open-channel flow MCERT applications
Monitoring Certification (MCERT) schemes are independent programs created to give firms a framework for meeting quality standards.
The first three most accurate devices mentioned under class 1 certification are ultrasonic, with a combined accuracy of 0.04 percent, as opposed to radar on the same scheme, which has a class 2 certification with a combined accuracy of 0.22 percent.
However, in those applications, more than a few meters of the measuring range, radar does have its advantages.
High-temperature applications
A temperature gradient may be created above the surface of the substance being measured in cases where the surface is hot.
This will have an impact on sound speed and result in an erratic ultrasonic signal, which will essentially lower measurement accuracy.
Acoustic noise interface
Ultrasonic measurements with low voltage and strong acoustic power can overlook electrical noise interference.
However, occasionally acoustic noise can obstruct the transmission. For these applications, a radar sensor can get rid of this unusual occurrence.
Foamy applications
In frothy situations, radar measurement will yield more consistent data than an ultrasonic sensor with insufficient sound output.
This is because the foam obstructs the ultrasonic transducer’s signal.
A sensor with excellent acoustic control can be used.
Both technologies can’t see through the foam to the liquid surface, which is one thing they have in common.
Dosing plants and intermediate bulk containers (IBCs)
Radar has the ability to read through container walls, which is one of its features.
In chemical dosing facilities, where chemicals are provided in plastic IBC tanks, this is helpful.
Because plastic has a low dielectric constant, users can precisely gauge stock and usage levels without adding a new process connection to the container.
Digesters
The inability of an ultrasonic system to measure accurately in the methane-rich, hot and pressurized atmosphere of a sludge digester has been one of its long-standing problems.
Radar measurement is viewed as a technique to assess levels within the digesters by adhering to a standardized set of communications and protocols that connect with the rest of the site, with businesses making an attempt to be environmentally friendly with biogas generation.
Regardless of what a user is tracking or trying to accomplish.
They may relax knowing that ultrasonic measurements will get the desired results.
However, for the 5% of situations mentioned above, the radar will provide a solution.
Users must make sure they select a retrofittable controller with both technologies because it is one factor that will be crucial to the results of a measurement.
They must make sure they have a control system that enables them to do that role in the event that the application suddenly changes or the conditions of the process change and they need to switch from one technology to another.
Having a control system with the flexibility for both technologies ensures that these decisions can be made quickly, without having to retrain engineers or having the expense of installing a new control system.
Also, servicing with on-site maintenance is made simpler.
The user will only need one set of control spares meaning only one set of instructions to learn.
These choices can be made rapidly without the expense of establishing a new control system or the need to retrain engineers by having a control system that is flexible for both technologies.
Additionally, servicing is made easier with on-site maintenance.
The user will only require one set of spare controls, which means they will only have to memorize one set of instructions.
Source: pulsar measurement