Precautions for Using Ultrasonic Level Meters
Abstract: Ultrasonic level meters are widely used in water environments, acids and alkalis, sludge, food, and many other applications.
An ultrasonic level meter is a digital level instrument controlled by a microprocessor. During measurement, pulsed ultrasonic waves are emitted by the sensor. The sound waves are reflected off the liquid surface and received by the same sensor, which converts them into electrical signals. Ultrasonic level meters feature automatic power adjustment, temperature compensation, and anti-interference functions. Because they use non-contact measurement, the measured medium is almost unaffected. Ultrasonic level meters are widely used in water environments, acids and alkalis, sludge, food, and many other applications.
Precautions for Using Ultrasonic Level Meters
I. Range and Size
The size of the object to be detected by the ultrasonic level meter directly affects the maximum range of the ultrasonic sensor. The sensor must receive a certain sound level before it can produce an output. Large objects reflect most of the sound back to the ultrasonic sensor, allowing the sensor to detect the object at its maximum sensing distance. Small objects reflect only a small portion of the sound, significantly reducing the sensing range.
II. Object to be Detected
The ideal object for ultrasonic detection using an ultrasonic level meter is large, flat, and dense, and positioned perpendicular to the front of the transducer. The most difficult objects to detect are those that are small and made of sound-absorbing materials (such as foam rubber), or objects positioned at an angle to the transducer. Some difficult-to-detect objects can be detected by having the sensor detect a background surface and then detect the target object between the sensor and the background.
Detecting liquids is easy if the liquid surface is still and perpendicular to the sensor surface. If the liquid surface is turbulent, the sensor's response time can be extended to average out the fluctuations and obtain more consistent readings. However, ultrasonic level meters cannot accurately detect liquids with a foamy surface, because the foam causes the sound waves to deviate from their path.
III. Vibration
Vibration—either from the sensor itself or from nearby machinery—can affect the accuracy of distance measurements. This issue can be reduced by using rubber vibration isolators when installing the ultrasonic level meter. In some cases, guide rails can also be used to eliminate or greatly reduce component vibration.
IV. Attenuation
The sensor is also designed with a temperature compensation function to adjust for slow changes in ambient temperature. However, it cannot adjust for temperature gradients or rapid changes in ambient temperature.
V. False Measurements
Objects near the ultrasonic level meter (such as guide rails or mounting rods) may reflect sound waves. To accurately detect the target object, the influence of nearby sound-reflecting surfaces must be reduced or eliminated. To avoid false measurements of nearby objects, ultrasonic level meters are equipped with an LED display that guides the operator during installation to ensure correct sensor mounting and reduce the risk of false readings.