Level measurement with radar;
radar type level transmitter, also called Radar level gauge.
Non-contacting radar is based on microwave technology,
which detects only surfaces that reflect energy.
In a measurement situation, temperature variations,
dust or pressure changes do not affect accuracy.
The device measures the time it takes for microwaves to leave the transmitter,
reflect on the media and return back.
The level is proportional to the time of flight.
With non-contacting technology,
it is also possible to calculate volume and mass.
Non-contacting radar technology is the ideal choice for tanks with moving objects,
and extreme temperatures and pressures.
It is also unaffected by media density. All this reduces maintenance needs.
Features of SIRD90 Radar Level Transmitters
The SIRD90 series radar sensor is a 26G HF radar level measuring instrument，with a maximum distance of up to 80 meters.
- Non-Contact Measurement
- Continuous Level Measurement
- Pulse Radar Measurement Range 0.254 to 15.24m (10″ to 50′)
- Simple Push-Button Calibration
- High measurement accuracy
- Measurement is not affected by temperature, pressure or dust
- User-friendly adjustment saves time
Applications of Radar level transmitters
- Solid materials;
- Process vessels or strong dust are easy to crystallize;
- Condensation occasions
- Solid Particles
- Slightly corrosive liquids
- Various corrosive liquids
- Hygienic liquid storage containers
- Strong corrosive containers
Parameters of SIRD90 radar level transmitter
- Measuring range: 70 meters
- Process connection: universal flange, thread
- Process temperature: -40～250°C
- Process pressure: -0.1～0.1MPa
- Accuracy: ±15mm
- Frequency range: 26GHz
- Explosion-proof grade: Exia IIC T6 Ga/ Exd [ia] IIC T6 Gb
- Protection level: IP67
- Live display: Four-digit LCD programmable
- Housing: Aluminum / Plastic
- Signal output: 4…20mA/HART (two lines/four lines) RS485/Modbus
How does a radar level transmitter work?
In radar level measurement,
microwaves are transmitted by the antenna system of the radar sensor,
to the measured product, reflected by the product surface,
and received back by the antenna system.
The time from emission to reception of the signals is proportional to the level in the vessel.
In continuous non-contact level measurement with radar,
the sensor sends microwave signals towards the medium from above.
The surface of the medium reflects the signals back in the direction of the sensor.
Using the received microwave signals,
the sensor determines the distance to the product surface
and calculates the level from it.
Liquids and solids are commonly measured with this measuring technique.
What is the difference between ultrasonic and radar level transmitters?
As the name implies, ultrasonic level sensors,
operate by emitting a burst of sound waves in very rapid succession.
These sound waves hit the intended target,
bounce back to the sensor,
and travel at known speed (the speed of sound).
We can calculate the time of flight and come up with a distance.
Radar, by contrast, works not with sound waves,
but with electromagnetic waves.
This is the key difference.
Like ultrasonics, the waves bounce off of objects,
and travel at a known speed (much faster than ultrasonic waves),
but they react differently to certain materials.
There is a different set of variables that affects how well a radar sensor operates.
Unlike ultrasonic sensors,
radar is much less affected by temperature,
improving consistency and accuracy.
Radar is also well suited for specialty applications,
such as working in a vacuum, or in higher pressures (as long as the housing can handle it).
An important factor is the target material’s dielectric constant. A mater
An important factor is the target material’s dielectric constant.
A material with a low dielectric will not reflect an electromagnetic wave,
so radar tends to pass right through.
These materials are typically non-conductive and have low moisture content,
such as dry powders and granules.
To be fair, radar can sense a lot of these materials,
but the energy of the returning waves is so small,
that precise alignment with the signal is paramount.
This introduces techniques such as guided wave radar, or special antenna.
Measuring materials with a low dielectric constant,
is not always impossible, just very challenging.
All with a low dielectric will not reflect an electromagnetic wave, so radar tends to pass right through.
These materials are typically non-conductive and have low moisture content, such as dry powders and granules.
Let’s see this video about: Ultrasonic Level versus Guided Wave Radar Level
How do you calibrate radar level transmitter?
- Set up the guided wave radar level transmitter,
- HART communicator, power supply,
- and the multimeter as below (see below calibration setup Diagram).
- Check the configuration of the lower range value (0% level, 4 mA) and high range value (100% level, 20 mA). Make sure that the inputted data is as per the datasheet.
For example, the lower range value is 10 inch and the high range value is 35 inch (both of it are measured from the bottom of level transmitter probe)
- Fill the level transmitter chamber with water up to the 0% level. Read the level measurement in the transmitter LCD (or in the HART communicator). Set this condition as 0% level through HART communicator.
- Read the mA output of the transmitter by using a multimeter. Adjust (if any) through the HART communicator so that the output of the transmitter (on the multimeter) is 4 mA.
- Fill the level transmitter chamber with water up to the 100% level. Read the level measurement in the transmitter LCD (or in the HART communicator). Set this condition as 100% level through HART communicator.
- Read the mA output of the transmitter by using a multimeter. Adjust (if any) through the HART communicator so that the output of the transmitter (on the multimeter) is 20 mA.
If you still have questions about radar type level transmitter calibration,
Sino-Instrument offers Radar level transmitters and Guided-wave radar (GWR) level transmitter.
Our radar level transmitters, Made in China,
can work as Rosemount radar level transmitter.
Improve Safety and Reliability While Enhancing Efficiency