Using an Ultrasonic Level Sensor

water depth sensing with sensors

water depth sensing with sensors

Ultrasonic Water Level Sensor Recommendations:

MB7052

MB7052 XL-MaxSonar-WRM1

Features of the weather resistant MB7052, XL-MaxSonar-WRM1, include small target rejection providing range information to the target with the largest acoustic return, a stability filter, centimeter resolution, short to long distance detection, range information from 20cm to 765cm, a 6.7Hz read rate, and various output options: pulse-width, analog voltage, and RS232 serial.

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MB7369

MB7369 HRXL-MaxSonar-WRM

Features of the weather resistant MB7369, HRXL-MaxSonar-WRM, include millimeter resolution, short to long distance detection, range information from 300mm to 5000mm to the target with the largest acoustic return, a 6.7Hz read rate, and various output options: pulse-width, analog voltage, and RS232 serial.

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MB7389

MB7389 HRXL-MaxSonar-WRMT

Features of the weather resistant MB7389, HRXL-MaxSonar-WRMT, include millimeter resolution, short to long distance detection, range information from 300mm to 5000mm to the target with the largest acoustic return, a 6.7Hz read rate, and various output options: pulse-width, analog voltage, and TTL serial.

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Can an Ultrasonic Sensor Detect Water Level?

Ultrasonic sensors are a popular choice for many liquid level applications. For non-contact water level detection, our sensors are IP67 rated for water intrusion. We offer an upgrade of our F-Option (which would make the sensor IP68 rated) which provides additional protection and improved performance in wet or dusty environments.

How an Ultrasonic Level Sensor Works

In a nutshell, water depth sensing is using a sensor to measure the depth of water in a tank or container. Although various sensors can be used for this application, we will talk about using ultrasonic technology in this application.

With ultrasonic sensors, we can find the water depth calculation by finding the distance between the transceiver and the surface of the water. The sensor will transmit a short ultrasonic pulse, and we can measure the travel time of that pulse (the echo) to the liquid and back. We can then subtract that distance from the total depth of the tank to determine the water depth.

For example, This project for a Low Power Water Level Sensor uses a sensor from our weather resistant line to measure the water level in a rainwater tank. Noted in the application here, the concept can be used to measure many things, such as snow and waste levels.

This method of measuring with ultrasonic sensors is more accurately described as water level measuring and used for water level control. In a tank or container, this will produce the same results. It is important to note, you would need to position the sensor at a fixed point above wherever the water is stored. This can have benefits over underwater submersion, including greatly increasing the overall lifespan of the sensor.

Underwater Use of Ultrasonic Sensors

As mentioned above, to truly measure water depth rather than water level with an ultrasonic sensor, we must submerge the sensor in water. We do not recommend this because our sensors were not designed for underwater use, and they have not been properly tested in this environment. Even though the MaxSonar-WR and MaxSonar-WRC lines are IP67 rated and can be submerged up to one meter, this goes against their intended function and will void the manufacturer's warranty. We cannot guarantee proper function if submerged.

Although this is not covered under our warranty, you can take a look at our article designed to help with underwater ranging . We can't necessarily support outside, underwater testing of our sensors, but we would love to hear about the results. Take a look at our MaxSonar-WR and MaxSonar-WRC product lines for reference.

Common Applications for Depth Measurement

Ultrasonic Depth Sensors aren't limited to only water detection and are used in a variety of applications including:
  • Tank level measurement
  • Diesel fuel gauging
  • Irrigation control
  • Stream or River level monitoring
  • Wet well and pump controls
  • Sea or Tide level monitoring and Tsunami warning
  • Liquid assets inventory

Case Studies for Level Detection

You can review our Collaborators page, which can point you to case studies of our sensors integrated into end-user applications for level detection. These are a few use cases of our WR sensors in which they're used in level sensing applications (primarily in tanks). Our sensors have successfully been used in many level detection use cases. Below are a few that you can review for reference: Radio Bridge - Long-range Wireless IoT Sensor
  • Level in Tanks - Radio Bridge provides full sensor to cloud solutions for Internet of Things applications. This solution is typically used in tank monitoring applications.
TECLAB | FAST - IoT Level Sensor
  • Channel Flow Measurement - This IoT level Sensor solution named Level-X is used to detect the level of water flowing in a channel while calculating the water flow for overflow channels.
ELSYS - LoRaWAN IoT Distance Sensor
  • Liquid Level Measurement - Sweden based company ELSYS uses our weather resistant sensor to solve problems like underwater level measurement, waste level measurement in containers and snow depth measurement.
If you are interested in measuring tank levels, check out our Guide to Tank Level Monitoring with Ultrasonic Sensors that might help answer some questions. We also have an article about using an ultrasonic sensor inside of a pipe that might provide some useful information on the above applications.

Mounting an Ultrasonic Level Sensor

When mounting the sensors in a tank, there are things to take into consideration when trying to maintain accuracy. The dimensions are important to be able to choose the proper sensor beam pattern for your application. If the tank walls are corrugated, it is important to take that into consideration when selecting your sensor, the sensor may not range past the walls to the surface. Note: The MB7389 comes with the most likely filtering to help resolve this issue. The sensor will search for the largest acoustic return, instead of the closest. This helps to hide the side walls of the tank from the sensor and provide readings with more accuracy.

Monitoring Lake Levels with Ultrasonic Sensors

While all of our sensors can be used for liquid level detection, none of our sensors were designed for bathymetry (the measurement of the depth of water in oceans, seas, or lakes). The only way you could use our sensors to measure the depth of a lake would be to mount it a known height above the lake bed and subtract the reported distance to the water (the sensors reading) from the known distance to the lake bed. (Same concept as measuring levels/depth in a tank or container). If you would like help selecting a sensor for any application, please email us at techsupport@maxbotix.com

Ultrasonic Sensors Vs. Other Solutions in Level Sensing

Float switches and optical sensors may be more likely to corrode in level sensing applications.

Ultrasonic sensors are a non-contact level measurement component which doesn't make contact with the liquid.

For level sensing applications using an ultrasonic sensor, we highly recommend the use of our WR sensors, which are IP67 rated.

For added protection in liquid level sensing applications we recommend the following: F-Option - A Fluorosilicone sealant for more protection. This chemically inert seal will help protect the sensor in harsh environments. P-Option - This Parylene coating is for improved corrosion resistance. This coating is applied to the surface of the aluminum transducer. Shielded Cable Attach - The Wire-Attach Option uses the MaxSonar MB7954 Shielded Cable with a sensor cap to fully protect the pin-out of the MaxSonar sensor. It will create a completely IP97 rated sensor, and includes 3ft of wire. You can review our Chemical Compatibility Chart for more information about our sensor requirements for certain environments.

Common Questions about using an Ultrasonic Level Sensor:

Can I use the WR sensors underwater? (Do you have an underwater sensor?)

The MaxSonar-WR and MaxSonar-WRC sensors are IP67 rated and can be submerged (up to one meter) but the sensors are not designed to range underwater. The primary reason is because of the change in the density and speed of sound through the water medium. We have had many requests to explore this type of ranging, however, we have decided not to go in the direction of underwater ultrasonic sensors at this time as it is outside our current company scope. Periodically, we will continue to reevaluate adding a product that is designed for underwater use.

Do I have to seal the backside of the sensor where the pinout is?

Yes, the front side of the sensor is IP67 rated, however, the user is still required to seal the pinout section of the sensor. We can easily do that for you if you add the shielded cable attach option when selecting your sensor. You can check out our article about weatherproofing the pinout.

Is the sonar made for use in an underwater environment?

The sensor is rated IP67 meaning it can tolerate submersion in water up to 1 meter deep (and with the F-Option it is rated IP68 three-meter submersion or even more). Do understand the sensor is not designed to operate when underwater. The F-Option provides additional protection for the ultrasonic transducers in the sensor component.

If the sonar is not meant for underwater use, how can you outfit it to work underwater?

If you use the analog envelope output, you could use the waveform and look for the underwater reflections in the waveform detected by the sensor. This would require an AD converter that sampled at regular intervals and then this data would show the distance to the target. Some users reported that they used the analog voltage output with success (it reported the wrong distance because ultrasonic sound waves travel at different speeds underwater, but they were able to use the measurements with lookup values).

How reliable are your sensors for level sensing?

Our level sensors are reliably used in many level detection applications. We tested our sensors rigorously and we maintain a MTBF of 200,000 hours.

What that means for you is, you can trust our product lifetime, as we have observed no failures in our hours of testing.

Is the sonar made for use in an underwater environment?

Our WR ultrasonic sensors are built for use in environments where water may be present.

They are IP67 rated which means they are rated as “dust tight” and protected against immersion for 30 minutes at depths of 150 mm - 1000 mm.

Not sure if our sensors would be the right fit for your application?

Click the button below to contact our team to discuss your project needs.
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