How to Select Ultrasonic Sensors: A Guide

How to Select Ultrasonic Sensors: A Guide

Image Credit: Senix Corporation

Ultrasonic sensors measure the distance from the sensor to an object via air without making physical contact. They calculate distance by emitting high frequency soundwaves (also known as ultrasonic soundwaves) towards the object being measured.

By receiving the reflected soundwave and calculating the time between emission from the source and reception back at the source, distance can be measured.

Ultrasonic distance measurement sensors can be used in a broad range of scientific and industrial applications where the non-intrusive capabilities of a measurement device are crucial.

Ultrasonic sensors are manufactured in a wide range of variants and specifications to adhere to differing measurement criteria and restrictions. This increases the likelihood, but also the potential complexity, of a customer finding a sensor that is appropriate for their unique application.

Senix specializes in the design, manufacture, distribution, and support logistics of high quality ultrasonic sensors. The company has over three decades of experience in supplying the appropriate non-contact distance measurement sensor to end-users and original equipment manufacturers (OEMs) in a wide range of sectors.

Choosing the right ultrasonic sensor involves taking a number of variables into consideration, including measurement application, output requirements, object distance and environmental conditions.

What is the Measurement Application?

Each non-contact distance measurement application may have different requirements and constraints. An ultrasonic sensor can be stainless steel for corrosive environment operations, for example, wireless-enabled for distant measurement or cross-talk-resistant for multi-sensor processes.

Typical Applications for Senix Ultrasonic Sensors 

  • Monitoring water levels to facilitate irrigation and track sea, stream, river and canal levels, plus flood and tsunami warning operations  
  • Calculating the flying height of hydrofoil and similar categories of vehicles
  • Measuring the distance of objects for positioning, dimensioning and object ranging purposes
  • Wirelessly transmitting levels in tanks, streams and other areas to remote authorized users
  • Measuring material levels in a container or vessel; for example, allowing the user to work out not only the current levels but if/when it should be refilled  
  • Detecting whether or not an object is present within a specified distance window

It is essential to factor in the chemical characteristics of the object being measured when deciding on sensor design and construction. Where water is being measured, a general purpose sensor may be appropriate. Alternatively, in instances where a strong chemical is being measured, it may be beneficial to use a more chemical-resistant model such as the ToughSonic CHEM.

What is the Maximum/Minimum Measurement Distance?

Should a sensor be too near an object, it may not be able to measure the distance accurately. Conversely, if a sensor is too distant from an object, it may be unable to detect the object in question.

Where a sensor is being selected for distance measurement applications, it needs to be correctly rated for the anticipated minimum and maximum measurement distances.

A number of factors should be considered when determining the required useful operating range, for example, the material window.

Material State

Solids and liquids will behave differently when interacting with soundwaves. In turn, this will result in different interactions with an ultrasonic sensor. A sensor with a range that is at least 25% greater than the expected maximum measurement distance is the most appropriate option for liquid measurement applications.

A sensor with a range that is at least 50% greater than the expected maximum measurement distance is the best fit for dry measurement applications.

Size, Shape, and Orientation

These three variables can affect the maximum distance at which a material can be detected by an ultrasonic sensor. For example, a large body of flat water will have a surface that is one of the easiest to detect at a distance.

By contrast, curved or granular items will be more difficult to detect at a sensor’s maximum range.

Senix ultrasonic sensors are available with a maximum measurement distance of approximately 50 ft. Maximum measurement distance ranges vary by model and application.

For example, hazardous area range is 25 ft, chemical area range is 35 ft, and general purpose area range is a maximum of 50 ft.

What Sensor Output is Preferred?

Ultrasonic sensor outputs are established based on the measurement reading. In specific circumstances such as override conditions, this may be based on the potential for the target not being detected or on user-selected response algorithms.

An ultrasonic sensor from Senix can provide singular or multiple concurrent outputs to various connected devices, including displays, computers and programmable logical controllers.

Output is available in three options:

Firstly, analog, where the voltage or current output signals will vary in proportion to the distance being measured.

Secondly, serial data, where the output data will be transmitted sequentially to a specified connected device.

Thirdly, switch/relay, where the switch outputs turn on or off at set distances, which in turn will start and stop specific exterior actions or indicators at pre-set distances.

It is highly relevant to factor in the type of system that a sensor will be plugged into, as well as the devices to be connected to a sensor. This should be done as part of the decision making process when choosing between the three output options.

What are the Application Environment Conditions?

To provide trustworthy distance measurement performance in a variety of industrial environments, ultrasonic sensors need to be engineered to specifications that withstand the conditions found in the environment in question.

There are a number of environmental factors to take into account when choosing an ultrasonic sensor.  


The speed of sound can vary, depending on the temperature. This can affect the precision of the distance being calculated between a sensor and a target object.


Environmental material build-up, such as snow, mud, dust and ice, can obstruct the sensor face. This may impede ultrasonic soundwaves from either being transmitted or received.


Contaminants may enter the ultrasonic sensor, affecting its function. The ToughSonic sensor range is constructed with full epoxy potting. The cables are UV-shielded and utilize NEMA-4X / IP68 / NEMA-6P or polymer or stainless-steel housings to ensure resilience in tough outdoor environments.


Ultrasonic sensors are not intended for use in vacuum or high-pressure applications.

Ultrasonic Noise

Ultrasonic noise from neighboring apparatus, for example, air nozzles, ultrasonic welders and pneumatic valves, can hinder measurement operations. Computable, programmable models can be configured to remedy these effects.

Senix Ultrasonic Sensors

Ultrasonic sensors can perform an essential role in a wide variety of non-contact distance measurement applications in critical operations. Senix ultrasonic sensors can be found in exacting distance measurement applications around the world.

This information has been sourced, reviewed and adapted from materials provided by Senix Corporation.

For more information on this source, please visit Senix Corporation.


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