1. What do Senix® ultrasonic sensors do?
Ultrasonic sensors measure the distance to or presence of a target object or material through air without touching it. The measured distance is provided as an output in a variety of standard electrical interfaces compatible with displays, machinery, PLC’s, computers and most electronic or electrical machinery.
Non-contact ultrasonic sensors have distinct advantages in challenging environments where corrosive, scaling, coating, or dirty materials are likely to negatively impact the performance and maintenance costs of contact sensors. Non-contact ultrasonic sensors are also desirable where the material being measured cannot be corrupted by contact with any measuring device.
2. What DON’T Senix® ultrasonic sensors do?
They DO NOT measure through tank walls – they only measure through air.
They DO NOT measure material thickness by contacting the material. Search non-destructive testing (NDT) sensors for that purpose.
They DO NOT work in a vacuum. Sound does not travel in a vacuum.
They DO NOT work at very high temperatures or pressures.
They DO NOT locate objects moving about in a 3-dimentional space.
They DO NOT measure farther than about 70 feet (21 meters).
They DO NOT measure at very high repetition rates. Due to speed of sound limitations the fastest rate is 200 Hz at a max distance of about 24 inches.
They DO NOT work as accurately in vapor environments that change the speed of sound from that of air.
3. Where are Senix® ultrasonic sensors used?
Ultrasonic sensors are used wherever non-contact distance measurement is desirable. Senix sensors are operating reliably on thousands of machines in all industries and many operating environments worldwide. Applications range from simple liquid level measurement to diameter measurements in converting machinery to robot positioning in automated warehouses. Senix can also configure, adapt or design sensors for special needs. Applications fall into three general categories:
LIQUID LEVEL MEASUREMENT − measuring the height of liquids
Industries monitor liquid levels in tanks, vats, drums, bins, lift stations, flumes, weirs and stilling tubes. Environmental monitoring applications measure the ocean surface for Tsunami warnings, river & stream levels for flood warnings and irrigation channels and ponds for water delivery. Where there is liquid there is usually a need for inventory or level control. Read more about Liquid Level sensor applications …
OBJECT DETECTION − detecting the presence of objects or people
Objects can be detected for security, counting, inventory or robotic obstacle avoidance. Ultrasonic sensors are not affected by the object’s color or optical characteristics such as reflectivity, transparency or opacity. People can be detected at kiosks, or determined to be approaching or leaving. Targets can be monitored over the full sensor range or restricted within user-defined distance ranges. Learn more about Object detection applications…
DISTANCE MEASUREMENT & DIMENSIONING − measuring location
Senix sensors can discriminate objects by height or size, such as when selecting and routing boxes on a conveyor or rejecting out-of-dimension objects. Converting machines measure changing roll diameter to control web tension. Other applications measure the location of a target object for display or control feedback. Examples include dancer roll and web loops in printing and converting machinery, camera focusing, mirror positioning in flight simulators, robotic positioning and much more. Learn more about Distance Measurement applications …
4. How do ultrasonic sensors work?
Ultrasonic sensors (sometimes called ultrasonic transducers), measure the distance to or the presence of a target object by sending a sound pulse, above the range of human hearing (ultrasonic), toward the target and then measuring the time it takes the sound echo to return. Knowing the speed of sound, the sensor determines the distance of the target and sets its outputs accordingly. Learn more about our technology …
Sensor outputs are set based on the measured distance, or under override conditions, a lack of target detection or user-selected response algorithms. Outputs can be:
• an analog voltage or current signal proportional to the measured distance
• Switches or relay contact closures that open or close at specific distances
• distance data transmitted digitally as serial data communications.
5. What kind of targets can Senix® sensors detect?
Sensors will detect both large and small targets, including liquids, solids and granular materials. The size, shape and orientation of the target will affect the maximum distance at which it can be detected. The sensor is not affected by optical characteristics such as color, reflectivity, transparency or opaqueness.
6. How far can Senix® ultrasonic sensors measure?
The maximum range of our products is presently 20 meters (about 70 feet) and varies by model. The distance at which an object is detected depends on its size, shape and orientation. In general the target must be larger to be detected at longer distances – the object must reflect a sufficiently strong ultrasonic echo back to the sensor to be detected. Large, flat targets such as a liquid surface in a tank are detected at the maximum range. Curved objects or sound absorbing materials such as fabrics or non-wovens reflect less energy directly back to the sensor. Granular materials may absorb sound or deflect sound energy away from the sensor due to surface variation and/or angle of repose. Sensor maximum range should be de-rated for these targets.
Other factors affect how close an ultrasonic sensor can be to a target and still measure distance correctly. When too close the sensor will not detect the first echo, but may detect a second or third echo, yielding a longer than actual value. This deadband distance varies by model and is larger for longer range models, varying from 44 to 305 mm (1.75 to 14 inches). The minimum range and maximum range define the limits of the material window, which is the useful operating range of the sensor. The material window is user-adjustable with SenixVIEW software to ignore unwanted targets or optimize system performance. When used outdoors we recommend limiting the range to the sensor’s “Optimum Range” specification rather than the “Maximum Range” to allow for environmental extremes.
7. How do I select the right sensor range for my application?
Selecting the right sensor range for your application will depend on many variables including target characteristics and the measurement environment. In liquid level applications, we recommend that you select a sensor range at least 25% greater than the maximum distance you are likely to measure. When measuring dry materials or difficult targets, we recommend selecting a sensor range at least 50% greater than your maximum measurement distance. Senix Customer Service can help you select the right sensor for your needs. Learn more about our sensors.
8. How accurate are Senix® Ultrasonic sensors?
Most Senix® models have a measurement resolution of 0.086 mm (0.003384 inches). Other measurement, environmental and target factors affect the overall result. Typical repeatability is better than 0.5%, and accuracy is better than 1% of the measured target distance.
9. Can ultrasonic sensors be used to protect the life or safety of people?
NO – DO NOT USE any ultrasonic sensor as a primary safety device to detect and protect people! Although ultrasonic sensors generally detect people reliably, an ultrasonic echo may not be detected if a person is at the wrong angle or is wearing ultrasonically absorbent clothing. Ultrasonic sensors can be used as secondary devices for additional safety, but they should never be used in an application where life or health are at stake!
10. How wide is the ultrasonic beam?
The ultrasonic beam angle in Senix® sensors is typically 10-15 degrees and conically shaped. The real-world response to an off-angle target has a lot to do with the target size and orientation, and the sensitivity setting of the sensor. Computer configurable sensors can be adjusted to optimize detection of the desired target and ignore undesired targets.
11. What happens if the ultrasonic beam hits other objects?
A common misunderstanding is that if the ultrasonic beam is larger than the target there is a problem. This is not true in general. It does not matter that the beam is larger or reaches other objects as long as those objects do not reflect sound back to the sensor or are farther away than the target of interest. For example, this means that a sensor can be mounted next to a wall or can measure inside a tube and the measurement will not be affected as long as the wall or tube surface is smooth because no sound energy is reflected back to the sensor from the surface. In computer configurable sensors, the detection of undesired or off-axis objects can be affected by beam width, sensitivity adjustment, range adjustment, processing filters and object masking.
12. How well do Senix® sensors work in industrial environments?
Sensors operate reliably in all but the most extreme industrial environments. They are used with electrically noisy machinery including motor drives and other electrical and electromechanical controls.
Specific considerations are discussed below.
Our ToughSonic line is IP68 / NEMA-4X / NEMA-6P rated and will operate after complete submersion.
The ToughSonic models are designed to withstand the harshest outdoor environment with full epoxy potting, UV shielded cables and stainless steel or polymer housings. The sensor face must be protected from buildup of ice, snow, mud and other debris or the transmission of sound energy will be reduced or blocked.