How do Ultrasonic Tank Levels Sensors Work?

How do Ultrasonic Tank Levels Sensors Work?

Ultrasonic waves detect an object in much the same way as Radar does it. Essentially Ultrasonic uses sound waves whereas Radar uses radio waves. In ultrasonic tank level monitors a signal is targeted towards the water, it is reflected from the surface and the echo returns to the sender. The time travelled by the ultrasonic pulse is calculated. This can then be used to calculate the current level of the water within the tank. 

This can be seen in the diagram below:


Figure 1: The basic principle behind an ultrasonic tank level meter 

The distance to the liquid surface is based on the speed of sound in air. This distance, D, is subtracted from the height of the tank, H, to give the depth, L, of liquid. The transmitter unit relays the level back to the LCD display to give you the current depth of your tank.

This principle in theory looks quite straightforward, however, in practice there are some limitations that need to be accounted for to ensure a correct level reading. These include:

•The velocity of sound changes with air temperature, as such tank level sensors should feature an integrated temperature sensor to compensate for these changes

•Interference echoes can occur from edges, welded joints and the software of the transmitter will compensate for this using interference echo suppression
•To ensure an accurate reading initial setup of the unit is critical, a correct depth and air gap will need to be set to ensure accurate readings.

The fundamentals of an ultrasonic sensor:

The ultrasonic sensor is the core of an ultrasonic tank level meter and this is what is giving you the ability to calculate your current water level. The sensor essentially translates electrical energy into ultrasonic waves. Piezoelectric crystals are used for this conversion process. Piezoelectric crystals will oscillate at high frequencies when electrical energy is applied to them. The reverse is also true. These piezoelectric crystals will generate electrical signals on receipt of ultrasound. These sensors are capable of sending ultrasound to an object and receive the echo developed by the object. The echo is converted into electrical energy for onward processing by the control circuit or LCD which gives you your current depth.

What we offer:

At Instrument Choice our core range of Tank Level sensors is the Aquatel Wireless Fluid Level gauges. They are a pioneer in the field and have developed Patented sensor cone technology which overcomes all issues around mixing humidity with ultrasonics. The Aquatel product line is used by many residential and trade professionals around the world including government departments like the Australian Corrections and US Military.

The D110 is our most popular option as it can be paired with up to 6 sender units. This allows you to monitor up to 6 tanks from 1 display. The D110 system comes complete with everything needed to remotely monitor one tank or cistern up to 300m/984 feet away or using Aquatel's AQ920-7 Booster Antenna kit (both ends), up to 10km/6 miles away. Should you wish to monitor more than one tank or cistern (up to 6 maximum) simply purchase additional T110 Tank Sender Units and pair to your Aquatel D110 Display Unit within minutes.


Another popular option is the M107-BT as it allows the user to set high and low level alarms, filling or draining fluid level, pump cut-in and cut-off points, set irrigation timer and manually switch on or off your pump/valve. Once levels have been set, the M107-BT will automatically monitor and maintain those fluid levels, so you can relax. Or when in Timer Mode, switch on and off your irrigation pump at the set times/days while at the same time monitor the supply tank to ensure your irrigation pump never runs dry. IC-M107-BT

If you have any questions regarding tank level monitoring please contact one of our friendly Scientists via email at [email protected] or via phone on 1300 737 871.

See our other newsletter articles here! 

Contact our expert scientists now to get the right meter or data logger to suit your needs and discuss your project. 

  Phone: 1300 737 871
[email protected]