Delivering Smart and Bluetooth-capable Radar Level Measurement

February 06, 2023 by Seth Price

Emerson’s new Rosemount level transmitters, equipped with Bluetooth for configuring devices during startup, power outages, maintenance, and troubleshooting, seek to improve water and chemical process safety and efficiency.

Emerson's latest Rosemount 3408 level sensors are designed for liquid measurement and aim to impact various industries. These sensors use a form of radar to ensure that no contact is necessary between the sensor and the transmitter itself. This reduces the sources of contamination, as there are no moving parts in the liquid compared to float-based level sensors. Besides the radar sensing element, these sensors are equipped with Bluetooth capability for configuring devices during startup, power outages, maintenance, and troubleshooting. 


Emerson Rosemount 3408 level sensor

The Rosemount 3408 non-contacting radar level transmitter. Image used courtesy of Emerson


Rosemount Level Transmitters

Rather than a float or a conductive tape to determine the liquid level in a tank, Emerson's Rosemount 3408 Level Transmitter uses a radar system. The radar emits an 80 GHz Frequency Modulated Continuous Wave (FMCW), a microwave signal that reflects off the surface of the liquid. The difference in frequency between the transmitted signal and the reflected signal can be used to measure the liquid level accurately, even in continuously changing, fast-filling, or fast-draining tanks. 

The sensing units are powered by 12-35 V DC and output a standard 4-20 mA signal capable of handling pressures from -15 to 363 psi. They can be ordered intrinsically safe with explosion-proof housings, making them suitable for environments with flammable vapors. 

Each sensor is Bluetooth capable, meaning paired devices can receive data up to 98 ft away from the transmitter sight, though individual results may vary. To configure the sensor or receive data, the device must be paired with the sensor. While no form of wireless communication is totally secure, the pairing action limits the chances of data or device control outside the facility.


Rosemount 3408 sensors are expected to benefit chemical industry

Rosemount 3408 sensors are expected to be used in several applications, including chemical storage and mixing tanks. Image used courtesy of Canva


Potential Applications and Industrial Impact

These sensors are expected to benefit the chemical industry, including storage and mixing tanks. In all of these applications, it is critical to know the level of tanks, reactors, and other process equipment. Keeping track of the level in this equipment means preventing overflowing and running equipment dry. 

Level control extends far beyond simply knowing the level in a tank. Consider a reactor that drains from the bottom due to gravity. The liquid level in the reactor will determine the output pressure at the bottom of the reactor due to hydrostatic pressure. This output pressure will further dictate the flow rate downstream and determine heat transfer through heat exchangers and other downstream effects. These effects can be modeled, calculated, and verified, provided the level is known.

The non-contacting radar limits contamination—there is no potential for oil or wear particles from moving parts to enter the liquid. Therefore, these Rosemount 3408 level sensors are suitable for drinking water utility houses, as well as food and beverage manufacturing operations. 

The Emerson Rosemount level sensors will see use when products need precise, quick level control measurements with very little chance of contamination.