The level measurement is made by emitting an ultrasonic pulse from the transducer, then measuring the time required for the echo to reflect from the liquid surface and return to the transducer. The powerful electronics measure the time of the round trip pulse and, by knowing the speed of sound, calculate the distance. Since speed of sound is temperature dependent, the transducer also measures the temperature in the vessel to provide compensation for changing temperature.
By inputting the type and geometry of the vessel, the intelligent electronics can calculate the liquid volume in the vessel. In a similar operation, the ultrasonic level switch can perform open channel flow measurement by converting the level reading into units of volume per time. Common tank shapes, flumes, and weirs are stored in the device’s software. A 32-point linearization table is also available for unusual tanks or primary flow elements.
The transducer is mounted above the maximum level of the media to be measured with the ultrasonic pulse directed at the surface of the media. As the level of the media moves, the time interval for the signal return also changes. The transmitter converts this time interval to a direct reading of level.
Ultrasonic non-contact transmitters are utilized for the measurement of liquid level, volume or open-channel flow. This technology features the ability to measure the level or volume of the fluid without making physical contact with the material. This is especially important in applications containing corrosive materials, suspended solids or coating media.