Level Detection with Ultrasonic Sensors

Liquid measurement can be a demanding application therefore selecting the most effective sensor technology is imperative. Ultrasonic sensors are the ideal solution for distance measurement or position detection of granules, fluids and powders. They measure fill levels, heights and sag without making contact as well as count and monitor the presence of objects. They are extremely versatile, operate independently of color and surface finish, and are not affected by transparent objects that generate strong reflections. And because they are not affected by dust, dirt and steam, they are the ideal choice for critical applications.

Ultrasonic Sensors operate with propagation of sound waves providing a reliable detection source for level detection applications where liquid measurement monitoring is necessary. They will enhance the flexibility of the application with additional advantages of being a non-contact sensor so there are no mechanical floats or arms that can retain residual liquid build up. This residual material can cause machine application downtime as interruption of production is needed to maintain and clean the mechanical monitoring system. Because the distance to the object is determined via a sound transit time, ultrasonic sensors have excellent background suppression. With their transit time measurement, ultrasonic sensors can record the measured value with highly precise resolution (some sensors to even 0.025 mm). Ultrasonic Sensors can monitor
and detect nearly any liquid.

Level Detection with Ultrasonic Sensors2Level Detection with Ultrasonic SensorsAn ultrasonic sensor is not affected by the color, transparency or glossiness of a surface. They can reliably detect bulk materials, liquids and material surfaces. Good reflective materials include:

  • „„ Water
  • „„ Paint/varnish
  • Wood
  • Metal
  • Plastic
  • Stone/concrete
  • Glass
  • Hard foam rubber

Additional advantages ultrasonic sensors provide when monitoring liquid is their ability to have two independent outputs programmed into one sensor. This is a great way to monitor upper and lower liquid levels with one sensor. This sensor feature allows one independent output setting to indicate a minimum level and the second output to indicate a maximum level concurrently providing constant feedback along with a voltage or current output.

4 Replies to “Level Detection with Ultrasonic Sensors”

  1. Hi Shawn – you’ll have to excuse my ignorance as I’m trying to do some research around fill level monitoring and the different ways to achieve this quickly and efficiently. What’s the major difference between the sensors that you mentioned in this article and the say something like http://www.peco-inspx.com/fill-level-monitoring-inspection.

    I get that one uses sound waves and the other uses some type of gamma x-ray, but what other differences should I be considering?

    I’m sure you’re a busy man, but thanks for you time!

    John H.

    1. Hello John,

      Thank you for the question!

      It appears that per your attached link… this is a complete integrated system that uses some type of x-ray to monitor the correct fill level from the side of a container. The main difference that stands out when using Ultrasonic sensors is that they would monitor the correct level from an opening in the top of the container so the cap cannot be present on the reservoir. When monitoring the level we can simple error proof the min and max level of the liquid with an analog output.

      Thanks again,

      Shawn D.

    2. Martin Lymn says:

      I think it’s ‘horses for courses’ – the ultrasonic solution requires the container to be open, leaving the risk, of course, that contents could get spilled after they’ve been ‘verified’. The Peco-InspX solution might arguably be overkill for an open container but has the advantage of being able to ‘look’ at the fill level through the wall of the container (even the steel wall of a food or paint can), with the container sealed — meaning that once the level is verified, there’s no risk of change in contents

      1. Hello Martin,

        I totally agree! There are certain technologies and sensing methods for each type of application. The described Peco-InspX solution is a total system that may be ideal for a high speed level detection where the Ultrasonic sensor is more ideal for controlled leveling applications with larger container openings. It really just depends on the application needs… Oh and of course price.

        Additionally… if a container wall needs to be ignored for level detection a Capacitive sensor could also be a great choice.

        Thanks and have a great day!

        Shawn D.

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