Download - Radar and Ultrasonic Level Measurement
8/7/2019 Radar and Ultrasonic Level Measurement
http://slidepdf.com/reader/full/radar-and-ultrasonic-level-measurement 1/24
Level Measurement with Radar and Ultrasonic
NorCal Tech 2005 Technical Conference
Level Measurement with Radar and
Ultrasonic
8/7/2019 Radar and Ultrasonic Level Measurement
http://slidepdf.com/reader/full/radar-and-ultrasonic-level-measurement 2/24
Level Measurement with Radar and Ultrasonic
Technologies
Through Air
Radar
Guided Wave
Radar
Ultrasonic
8/7/2019 Radar and Ultrasonic Level Measurement
http://slidepdf.com/reader/full/radar-and-ultrasonic-level-measurement 3/24
Level Measurement with Radar and Ultrasonic
How it works
The time it takes for the instrument¶s
signal to leave the antenna, travel to the
product, and return to the antenna is
calculated into distance.
The instrument is spanned according tothe distance the 100% and 0% points
within the vessel are from its reference
point .
The measured distance can then be
converted into the end user¶s desired
engineering unit and viewed on the head
of the instrument or remote display.
100%100%
0%0%
8/7/2019 Radar and Ultrasonic Level Measurement
http://slidepdf.com/reader/full/radar-and-ultrasonic-level-measurement 4/24
Level Measurement with Radar and Ultrasonic
How do process conditions affect the
reliability and accuracy of process
level transmitters ?
density (specific gravity)?
dielectric constant?
conductivity?
temperature?
pressure?
vacuum?
agitation?
vapors and condensation?
dust and build up?
internal structures?
Process conditions that affect specification of transmitters
8/7/2019 Radar and Ultrasonic Level Measurement
http://slidepdf.com/reader/full/radar-and-ultrasonic-level-measurement 5/24
Level Measurement with Radar and Ultrasonic
Through Air
Radar
8/7/2019 Radar and Ultrasonic Level Measurement
http://slidepdf.com/reader/full/radar-and-ultrasonic-level-measurement 6/24
Level Measurement with Radar and Ultrasonic
Radar Technology ± How it works
Radar is a time of flight measurement.
Microwave energy is transmitted by theradar.
The microwave energy is reflected off the product surface
The radar sensor receives themicrowave energy.
The time from transmitting to receivingthe microwave energy is measured.
The time is converted to a distancemeasurement and then eventually alevel.
8/7/2019 Radar and Ultrasonic Level Measurement
http://slidepdf.com/reader/full/radar-and-ultrasonic-level-measurement 7/24
Level Measurement with Radar and Ultrasonic
Function of an antenna
Signal focusing
� reduction of the antenna ringing
� optimization of the beam
Signal amplification
� focusing of the emitted signal
� amplification of the receipt signal
Signal orientation
� point at the product surface
� minimization of false echoreflections
8/7/2019 Radar and Ultrasonic Level Measurement
http://slidepdf.com/reader/full/radar-and-ultrasonic-level-measurement 8/24
Level Measurement with Radar and Ultrasonic
Radar level measurement
Top mounted
Solids and liquids applications
Non-contact
RADAR is virtually unaffected by the
following process conditions:
Temperature
Pressure and Vacuum
Conductivity
Dielectric Constant (dK)
Specific Gravity
Vapor, Steam, Dust or Air Movement
Build up (depends on radar design)
Radar Technology ± Why use it?
8/7/2019 Radar and Ultrasonic Level Measurement
http://slidepdf.com/reader/full/radar-and-ultrasonic-level-measurement 9/24
Level Measurement with Radar and Ultrasonic
Radar Technology - Choice of frequency
Radar wavelength = Speed of light / frequency
P = c / f
Frequency 6.3 GHz
wavelength P= 47.5 mm
Frequency 26 GHz
wavelength P= 11.5 mm
High frequency:
shorter wavelength
narrower beam angle
more focused signal
ability to measure smaller vessels
with more flexible mounting
47.5mm47.5mm
11.5mm11.5mm
Low frequency:
longer wavelength
wider beam angle
less focused signal
ability to measure in vessels with
difficult application variables
8/7/2019 Radar and Ultrasonic Level Measurement
http://slidepdf.com/reader/full/radar-and-ultrasonic-level-measurement 10/24
Level Measurement with Radar and Ultrasonic
5 GHz 10 GHzFrequency
Comparison of horn diameters that produce the same beam angle
20 GHz15 GHz 25 GHz
Focusing at 6.3 GHz:
Horn size Beam angle
3³ 38°
4³ 33°
66" 2121°°
10³ 15°
Focusing at 26 GHz:
Horn size Beam angle
1.51.5" 2222°°
2³ 18°
3³ 10°
4³ 8°
Radar Technology ± Focusing of Frequency
30 GHz
6.3 GHz6.3 GHz 26 GHz26 GHz
(A shorter wavelength means a smaller antenna for the same beam angle)
8/7/2019 Radar and Ultrasonic Level Measurement
http://slidepdf.com/reader/full/radar-and-ultrasonic-level-measurement 11/24
Level Measurement with Radar and Ultrasonic
Major Factors in Specifying a Radar - Frequency
Frequency
Choosing a frequency depends on:
Mounting options
Customer¶s 100% point
Vessel dimensions ± proximity
of connection to sidewall
The presence of foam
Agitated product surfaces
Vapor composition
Vessel internal structures Dielectric constant (dK)
8/7/2019 Radar and Ultrasonic Level Measurement
http://slidepdf.com/reader/full/radar-and-ultrasonic-level-measurement 12/24
Level Measurement with Radar and Ultrasonic
Radar Technology ± Choosing a frequency
Low Frequency ± 6.3 GHz ± C-band
Better Performance with:
Heavy Agitation Severe Build-up Foam Steam Dust
Mist Dish bottom vessels
Typical accuracy: +/- 10mm
High Frequency ± 26 GHz ± K-band
Small Process Connections
Very little ³near zone´
Recessed in nozzles
Less susceptible to false echoes
Reduced antenna size
Perfect for small vessels
� Able to measure lower dK
products without using a
stilling well.
Typical accuracy +/- 3-5mm
No single frequency is ideally suited for every radar level application.
8/7/2019 Radar and Ultrasonic Level Measurement
http://slidepdf.com/reader/full/radar-and-ultrasonic-level-measurement 13/24
Level Measurement with Radar and Ultrasonic
Guided Wave
Radar
(TDR)
8/7/2019 Radar and Ultrasonic Level Measurement
http://slidepdf.com/reader/full/radar-and-ultrasonic-level-measurement 14/24
Level Measurement with Radar and Ultrasonic
Guided Wave Radar Measurement
Guided Wave Radar level measurement
� Time of Flight
� Top mounted
� Solids and liquids applications
� Contact Measurement
� GUIDED WAVE RADAR is virtually unaffected by
the following process conditions:
Temperature
Pressure and Vacuum
Conductivity
Dielectric Constant (dK)
Specific Gravity
Vapor, Steam, or Dust Air Movement
Build up (depends on type of build up)
Foam
8/7/2019 Radar and Ultrasonic Level Measurement
http://slidepdf.com/reader/full/radar-and-ultrasonic-level-measurement 15/24
Level Measurement with Radar and Ultrasonic
Principle of Operation
�A microwave pulse (2 GHz) is
guided along a cable or rod in a20´ diameter or inside a coaxial
system.
�The pulse is then reflected from
the solid or liquid, back to thehead of the unit.
�The travel time of the pulse is
measured and then converted to
distance.
8/7/2019 Radar and Ultrasonic Level Measurement
http://slidepdf.com/reader/full/radar-and-ultrasonic-level-measurement 16/24
Level Measurement with Radar and Ultrasonic
Application Examples
� Installation into the vessel
� Installation in bridles without
worry of build-up or
interference from side leg
connections
� Ideal for replacement of
displacers
8/7/2019 Radar and Ultrasonic Level Measurement
http://slidepdf.com/reader/full/radar-and-ultrasonic-level-measurement 17/24
Level Measurement with Radar and Ultrasonic
Application Examples
� Interface Measurement
� Oil/Water
� Solvent/Water
8/7/2019 Radar and Ultrasonic Level Measurement
http://slidepdf.com/reader/full/radar-and-ultrasonic-level-measurement 18/24
Level Measurement with Radar and Ultrasonic
Guided Wave Radar ± Accuracy & Dead Zones
Typical Accuracies
� Cable +/- 5 mm
� Rod +/- 5 mm
� Concentric Tube +/- 3 mm
Typical Dead Zones or Blocking Distances
Cable
� Top 6 inches
� Bottom 9.8 inches
includes weight ± 6´
Rod
� Top 6 inches
� Bottom 0 inches
Concentric Tube
� Top: 1.6 inches
� Bottom: 0.8 inches
8/7/2019 Radar and Ultrasonic Level Measurement
http://slidepdf.com/reader/full/radar-and-ultrasonic-level-measurement 19/24
Level Measurement with Radar and Ultrasonic
Ultrasonic
8/7/2019 Radar and Ultrasonic Level Measurement
http://slidepdf.com/reader/full/radar-and-ultrasonic-level-measurement 20/24
Level Measurement with Radar and Ultrasonic
Ultrasonic Level Measurement
Ultrasonic level measurement
Time of Flight
Top mounted
Solids and liquids applications
Non-contact
ULTRASONIC is virtually unaffected by thefollowing process conditions:
Change is product density (spg)
Change in dielectric constant (dk)
8/7/2019 Radar and Ultrasonic Level Measurement
http://slidepdf.com/reader/full/radar-and-ultrasonic-level-measurement 21/24
Level Measurement with Radar and Ultrasonic
Ultrasonic Level Measurement ± How it works
Time of Flight Technology
Short ultrasonic impulses emitted fromtransducer
Bursts are created from electrical energy
applied to piezeo electric crystal inside thetransducer
The transducer creates sound waves(mechanical energy)
With longer measuring ranges a lower frequency and higher amplitude are needed
to produce sound waves that can travelfarther
The longer the measuring range thelarger the transducer must be
8/7/2019 Radar and Ultrasonic Level Measurement
http://slidepdf.com/reader/full/radar-and-ultrasonic-level-measurement 22/24
Level Measurement with Radar and Ultrasonic
Ultrasonic Level Technology ± Advantages
Can be mounted in plastic stilling wells
Narrow beam angles minimize effect of
obstructions
Swivel flange available for applications with
angles of repose
Familiar technology throughout the industry,
therefore, often a trusted technology throughout
the industry
Cost-effective
8/7/2019 Radar and Ultrasonic Level Measurement
http://slidepdf.com/reader/full/radar-and-ultrasonic-level-measurement 23/24
Level Measurement with Radar and Ultrasonic
Ultrasonic Level Technology ± When to use it
Vessels with products whose characteristics
remain constant
Water
Bulk solids
Storage Vessels
Where repeatability is not critical
Typical Accuracy +/- 5-10 mm
8/7/2019 Radar and Ultrasonic Level Measurement
http://slidepdf.com/reader/full/radar-and-ultrasonic-level-measurement 24/24
Level Measurement with Radar and Ultrasonic
Questions?
Questions?