
Ultrasonic Level Transmitters

Ultrasonic level transmitters are devices that use the principles of ultrasonic wave propagation for level measurement. These transmitters are usually non-contact type instruments, which means they do not require any physical contact with the material or liquid being measured.
An ultrasonic transmitter works by emitting an ultrasonic pulse from an ultrasonic transducer, which is a kind of ultrasonic sensor. This pulse then travels through the air until it hits the liquid surface (or material's surface) which reflects it back to the transducer. The time it takes for the pulse to return is directly proportional to the distance between the sensor and the liquid surface. The sensor measures this 'time of flight' and uses the speed of sound in the air to calculate the distance.
The ultrasonic level sensors can provide continuous level measurement and they are suitable for a variety of applications including tank level monitoring, object detection, and presence or absence detection in various materials and liquids.
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More Information about Ultrasonic Sensor Transmitters
One of the advantages of using ultrasonic level transmitters is that they are suitable for use in dusty environments and can handle build-up of materials. Additionally, since they do not require contact with the material being measured, they are also appropriate for use with corrosive or harmful substances.
The ultrasonic transmitters usually come with automatic temperature compensation. Since the speed of sound is affected by the temperature of the air, these transmitters are designed to compensate for changes in air temperature to ensure accurate measurements.
However, these devices may experience difficulty in heavy vapors or extreme temperatures. High concentrations of airborne particles or heavy gas vapors can absorb the ultrasonic wave and cause attenuation, thereby reducing the effective range of the sensor.
The unwanted echoes or 'dead bands' can also cause challenges in the signal interpretation. Dead band is a range close to the transducer where the device cannot accurately measure the level. Most models have built-in software to filter out false echoes and other acoustic interferences to provide reliable level measurement.
FAQs
What is the ultrasonic level measurement range generated by ultrasonic sensors?
The range of ultrasonic level measurement generated by ultrasonic sensors can greatly vary depending on the specific model and application. In general, these sensors can measure distances from a few centimeters to several meters.
Transmitters vs Transducers
Some of the most common types of transmitters and transducers can be found on pressure instruments. Examples of these include: drop-in well pressure devices and devices that measure the pressure in a pipe or gas chamber. Transmitters and transducers can also be found on flow and speed measurement devices.
What is the difference between transmitters and transducers?
The main difference is the way they send data to the monitoring device, like a PLC. In terms of measurement, the transmitter will reference a measuring unit by sending a milliamp signal (such as 4-20 mA). A transducer will reference a measuring unit by sending a voltage signal, typically in volts or millivolts.
Why have the two different types of transmission methods?
The method will depend on the application. If the electrical connection in the application travels a short distance, a pressure transducer is the better choice. Pressure transducers are smaller with fewer active electronic components that can be upset by electromagnetic interference. Also, the voltage signals transmitted over longer distances are subject to voltage drop and signal corruption. A transmitter is better for transmitting signals over a long distance.