Brian Craig
January 13, 2021
Level measurement is essential in several process applications to keep track of the fluid level in a process in terms of volume or weight. This can be done using a level measurement transmitter. It is an instrument or device that is used to determine the level of liquid or bulk solids at a given time. These transmitters are different from level switches, which sound an alarm when the level of the fluid inside reaches a predetermined level. Different types of level transmitters are used to control the level of liquids or semi-solid substances in a pressure tank or vessel. Radar level transmitters and ultrasonic level transmitters are most popularly used for level measurement. Both the transmitters can measure flow rates in all types of open channel flow applications. But what makes them so different from each other? This post discusses everything about radar level transmitters and ultrasonic level transmitters in detail.
Radar level transmitter, popularly known as guided wave radar level transmitter (GWR), is a contact-based level measurement method that follows the principle of Time Domain Reflectometry (TDR). They make use of a probe that guides high-frequency electromagnetic waves as they travel from a transmitter to the media that is being measured. With the TDR measurement technique, low-energy electromagnetic waves are transmitted along with the probe, which traverses into the process media, and their partial energy is reflected in the sensor circuitry. The fluid level is calculated by considering the time difference between the sent and the received pulses. Unlike other level measuring techniques, a guided wave radar level transmitter measures readings that are independent of the physical or chemical properties of process media. These transmitters work well in both solids and liquids.
Unlike radar level transmitters, ultrasonic level transmitters use a non-contact level measurement technique. The transmitter uses a piezo-electric transducer to emit mechanical waves. They operate by sending a sound wave to the process media that is being measured. A precise level measurement depends on the signal from the process media to the transducer. However, there are various factors that can affect the returning signals including heavy vapors, surface turbulence, dust, tank obstructions, and many more. Therefore, it is important to consider the characteristics of sound when using ultrasonic level measurement.
The following are some important differences between two-level measurement transmitters:
A radar level transmitter, often called a guided wave radar level transmitter (GWR), is a contact-based level sensor. It uses Time Domain Reflectometry (TDR) to send high-frequency electromagnetic pulses down a probe into the process media. As the pulse hits the media surface, part of it reflects back. The device calculates level based on the time it takes for the signal to return.
Key advantages:
An ultrasonic level transmitter is a non-contact device that uses a piezoelectric transducer to emit ultrasonic sound waves. These waves travel through the air and reflect off the media surface. The transmitter calculates the level based on the time delay between emission and echo reception.
Factors affecting performance:
Now that the difference between radar transmitters and ultrasonic transmitters is known, you can choose the appropriate one for your application. When choosing level transmitters for your applications, don’t compromise on quality as it can make a huge difference. You should source them from a trusted manufacturer or supplier like The Transmitter Shop. Over the years, the company offers high-quality and performance-driven level transmitters.
Radar uses microwaves and is less affected by environmental variables. Ultrasonic uses sound waves and is more susceptible to vapors, dust, and surface conditions.
Use it when accuracy is critical and the environment is harsh—such as in high-pressure, high-temperature, or vapor-heavy conditions.
Radar transmitters may be more expensive and might not be necessary for simple, non-hazardous applications. Some models also require grounding for optimal performance.
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