A presentation on level measurement which covers some of the technologies used in industries, advantages and disadvantages of level measurement products, do's and don'ts, mounting positions,etc. Also drafted a comparison table of all products at the end of presentation for better understanding.

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PRESENTED BY: CHETNA YADAV

2. CONTENTS
• INTRODUCTION TO LEVEL MEASUREMENT
• CLASSIFICATION OF LEVEL MEASUREMENT TECHNOLOGIES
• PRODUCTS OF LEVEL MEASUREMENT
• GUIDED RADAR LEVEL
• NON CONTACTING RADAR
• ULTRASONIC LEVEL MEASUREMENT
• RADIOMETRIC LEVEL MEASUREMENT
• ACOUSTIC PHASED ARRAY
• MICROWAVE BARRIER LEVEL MEASUREMENT
• COMPARISON TABLE OF ALL THE PRODUCTS
• REFERENCES
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3. What is level measurement?
• Level measurement is the
determination of the linear
vertical distance between a
reference point (usually the
base of a holding container)
and the surface of either a
liquid, the top of a solid, or
the interface of two liquids.
Precise control of the level of
liquid in a tank, reactor, or
other vessel is important in
many process applications.
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4. 4
Why is level measurement
required?
to keep track of
inventory in terms of
volume or weight i.e.
inventory management.
for reliable and
accurate inventory
control in a tank
gauging system.
Efficient use of storage
space prevents the extra
cost of needlessly
acquiring more storage
vessels.
For preventing
overfills and
leak detection.

5. Classification
of level
technologies
Level measurement devices can be
organized into the following five
categories:
1)Manual/mechanical (traditional
method)
2)Electromechanical (traditional
method)
3)Hydrostatic (traditional
method)
4)Electronic contacting (widely
used)
5)Electronic non-contacting
(widely used)

6. Products:
• Guided radar level measurement
• Non contacting radar level measurement
• Ultrasonic level measurement
• Radiometric level measurement
• Acoustic phased array level
measurement
• Microwave barrier measurement

7. Level measurement category Continuous level Point level
Guided wave radar x
Ultrasonic x
Radiometry/nuclear x x
Acoustic phased array x
Microwave barrier x
• Continuous level: determines the exact amount of substance in certain
place
• Point level: only indicates whether the substance is above or below the
sensing point.
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8. Guided radar level
• Guided radar level measurement is
well suited to liquids and bulk
solids.
• Turbulent liquid surfaces or foam
formation as well as different angled
surfaces or outflow funnels, as the
occur in bulk solids, do not
influence the measurement.
• Guided radar is also the first
choice for interface measurement.
• Measuring principle: time of flight
• In a guided wave radar installation,
the GWR is mounted on the top of the
tank or chamber, and the probe
usually extends to the full depth of
the vessel.
• A low energy electromagnetic pulse,
travelling at the speed of light, is
sent down the probe. At the point of
the liquid level (air / water
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9. Guided radar level
• The transmitter measures the time
delay between the transmitted and
received echo signal, and the on-
board microprocessor calculates the
distance to the liquid surface
using the formula:
• Distance = (Speed of light x time
delay) / 2
• Some applications that GWR is
commonly used in is paint, latex,
animal fat, soy bean oil, saw dust,
carbon black, titanium
tetrachloride, salt, and grain to
name a few.
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10. Advantages
and
Disadvantages
Advantages
• Reliable measurement:
Unaffected by medium
surfaces and tank obstacles
or baffles
• Safe measurement also
during filling
• Flexible interface
measurement with no moving
parts.
• 2-wire
Disadvantages
• Pull force dependent
• Wear on probe
• Inferred volume

11. Probe selection
• Coaxial probes: most efficient
• Twin element probe: less efficient
• Single element probe: least efficient
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12. G=Good, NR=Not Recommended, AD=Application Dependent, 12

13. G=Good, NR=Not Recommended, AD=Application Dependent
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14. Blind zones
• Measurements close to blind zones will have reduced
accuracy.
• In the blind zones, the accuracy exceeds ±1.18 in.
(30 mm), and
measurements may not be possible.
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15. Mounting position of transmitter
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16. Do’s
• Always install the probe in an empty silo and regularly
inspect the probe for damage.
• For solids, use the 0.24 in. (6 mm) probe, because of
the higher tensile strength. The probe should have a
sag of >=1 in./100 in. (1 cm/2.54 m) to prevent probe
damage
• Mount the probe as far away as possible from filling
and emptying ports. This will minimize load and wear
and will help to avoid disturbances from the incoming
product.
• The flexible single lead probe is recommended for
solids
• It is recommended that the vessel be empty during
installation.
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17. Don'ts
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• The probe should not come into contact with the
nozzle or other objects in the tank

18. 18
• Air technology, which emits narrow
microwave pulses down the cone shaped
antenna.
• The microwave signal comes in contact
with the measured medium surface and
reflects back to the antenna. The
signal is transmitted to the
electronic circuit and partly
converts to level signals.
Non contacting radar

19. Advantages and disadvantages
advantages
• It has no restrictions with respect to the weight of
the material so it can be used in applications where
guided wave radar may not be appropriate because of
pull forces or concerns about probe breakage.
• Non-contacting radars can see more of the surface than
guided wave radars, so will be slightly more accurate.
As a radar device, they react quickly to level changes
so are also appropriate for process applications and
small vessels.
• Since the probe doesnt need to come in contact with the
media, it is great for industries such as food and
beverage, medical, chemical and petrochemical, and oil
and gas
Disadvantages
• dust can be sticky and create a layer on the antenna.
If this layer becomes too thick, it may affect the
measurement.
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20. GWR Vs PULSE RADAR
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GUIDED WAVE RADAR PULSE RADAR
MEASUREMENT PRINCIPLE High-Frequency Radar Impulses Microwave Pulses
CONTACT TYPE Contact Measurement Non-Contact Measurement
ENVIRONMENTAL AND
APPLICATION CONDITIONS
Extreme Temperature and
Pressure Do Not Effect Device
Performance
Air Space Determines
Measurement Accuracy (not ideal
for extremely difficult applications)
MOUNTING Top Mounted (not ideal if there is
a mixer or other obstacle in the
tank
Top Mounted
COST Moderately Priced Cost-Effective
OVERALL PERFORMANCE Exceptional
Performs Well Independent of
Process Conditions
Acceptable
Performance is Based On Strength
of Reflection and Surface
Conditions

21. Ultrasonic level measurement
• Measuring principle: Prosonic is based on the Time-of-Flight
principle. A sensor emits ultrasonic pulses, the surface of
the media reflects the signal and the sensor detects it
again. The Time-of-Flight of the reflected ultrasonic signal
is directly proportional to the distance travelled. With the
known tank geometry the level can be calculated.
• Ultrasonic level measurement with Prosonic sensors provides
continuous, non-contact and maintenance-free level
measurement of fluids, pastes, sludges and powdery to coarse
bulk materials.
• The measurement is unaffected by dielectric constant,
density or humidity and also unaffected by build-up due to
the self-cleaning effect of the sensors
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Ultrasonic level
transmitter
Ultrasonic pulses
level

22. Advantages and disadvantages
advantages
• Non-contact, maintenance-free measurement
• Measurement unaffected by media properties, like dc
value or density
• Calibration without filling or discharging
• Self-cleaning effect due to vibrating sensor diaphragm.
disadvantages
• The ultrasonic level measurement is comparatively
expensive.
• If heavy foam is present on the surface it acts as an
absorbent which creates errors.
• Velocity of sound changes due to the variation of air temperature. An integrated
temperature sensor is used to compensate for changes in velocity of sound due
to temperature variations.
• There are some interference echoes developed by the edges, welded joints etc.
This is taken care by the software of the transmitter and called interference echo
suppression.
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23. Do’s and don’ts
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24. Sludge blanket
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• It can detect unclear sludge layers in a
purifying tank, thickener, etc. with a high
degree of accuracy..
• It enables continuous and real-time
measurement.
• It is provided with a logger that can store
10,000 points data at the maximum.
• Wiring cost can be reduced by the
optional wireless system.
• Maintenance loads can be reduced
significantly by the automatic cleaning
method.

25. Radiometric level measurement
• It consists of a source
container and Gamma pilot
which provides reliable
measurement values where other
measuring principles can not
be used anymore due to extreme
process conditions like high
pressure, high temperature or
because of mechanical,
geometric or construction
conditions.
Measuring principle
• The gamma source emits gamma
radiation which is attenuated
as it passes through
materials. The measuring
effect results from the
absorption of radiation by the
product to be measured which
is caused by level changes.
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26. Advantages and disadvantages
advantages
• Non-contact measurement from outside, non invasive, no
wear and tear.
• Easy installation
• Universally applicable on all kinds of vessels, without modification of the plant
• The radiation of the gamma source container is emitted
almost unattenuated in one direction only, and is
damped in all other directions. This guarantees highest
safety for a reliable measurement.
Disadvantages
• External radiation may affect the measurement.
• Large density changes, especially the density of
Hydrogen in a material, can create errors.
• In order to use the nuclear technology, licensing and
leak checks are required, as well as a high degree of
health and safety checks and care over source handling
and disposal.
• It is relatively expensive.
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27. Acoustic phased array
• The device includes an
integral array of three
antennas that generate
unique dust-penetrating low
frequency acoustic waves
and receive echoes from the
contents.
• Using these antennas, the
unit measures both the
time/distance of each echo,
and its direction.
• Collecting multiple echoes
from different directions
and distances enables the
device to accurately
calculate the volume of
stored material and allows
for a 3D visualization of
the material. 27

28. Advantages and disadvantages
advantages
• can measure practically any kind of solid material
stored in bins, silos, warehouses, and domes.
• The device can measure ranges of up to 230 ft (70 m)
and can generate 3D visualization of the material
surface.
• self-cleaning capabilities prevent material from
adhering to the internal workings of the antenna array,
ensuring long-term reliable performance with very low
maintenance requirements, regardless of harsh dusty
conditions.
Disadvantages
• Wrong mounting location may result in erroneous
measurements or loss of performance.
• The device is less suitable for narrow silos (Less than
6.56 ft. (2 m)). 28

29. Do’s
• Mounting in a specific orientation is important .The
antennas should be at least 10 mm inside the vessel and
mounted perpendicular to the ground. Antennas should be
directed toward the center of the vessel.
• The following factors must be taken into consideration
while choosing the installation
• position:
• Vessel dimensions
• Filling and emptying point locations
• Internal structure or support
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30. Don'ts
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• It is important to know the
location of any obstacles in
the vessel. Some obstacles may
affect the measurement and
this would impact the suitable
device location. The following
obstacles are common and
important to identify before
deciding on the Rosemount 5708
location:
1. Inlets
2. Internal structures
3. Ladders
4. Support beams
5. Thick roofs
• If the obstacle cant be
avoided by relocating the
device, a neck extension can
be used to extend the antenna

31. Microwave barrier level measurement
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• The microwave barrier switch
can detect the presence or
non-presence of materials
inside containers without
making any contact with the
actual materials inside.
• The absorption of microwaves
is used for the supervision
of limit values in microwave
barriers. The microwave
emitter and receiver form a
radiation barrier. A narrow
beam runs through the tank on
the level which is to be
monitored.
• As soon as the medium enters
the radiation area, the
microwave signal is damped so
that only a small part
reaches the receiver. This is
recognized and used for

32. Microwave barrier level measurement
• Non-contact point level detection in bulk solids.
• In many cases where contact methods are limited,
microwave barriers are the appropriate solution.
• They avoid jamming, indicate point levels, solve
positioning and counting tasks, provide non-contact
measurement and are thus, free of wear and tear.
• Typical products to be measured are wood chips, paper
and carton chips, lime, pebbles, sand or even bags and
complete boxes.
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33. Microwave barrier level measurement
Measuring Principle: Microwave barriers are used to
detect all kind of bulk solids based on microwaves
(transmitter/receiver-principle). The detection of bulk
solids movement (present / not present) is based on the
Doppler effect of the microwaves.
Applications
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34. Advantages and disadvantages
advantages
• Point level detection of high-purity fluids right
through the vessel wall, no openings required
• Microwave barrier is never in contact with the medium,
sensor cannot get soiled
• Wear and maintenance free operation over long periods
Disadvantages
Point level detection.
More instruments are used so high probability of
failure.
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35. technology type of material Maintenance cost Surface condition Measuremen
t technique
do’s Dont’s
Guided wave
radar
Liquid/liquid interface,
liquid,foam, powders,
grains.
better suited to dry
product applications.
Minimal
maintenance
And easy installation
Can tolerate
turbulence and
foam.
Electronic
contacting
suited for smaller
vessels with diameter
<33ft.
If the application
tends to be sticky or
coat, then only single
lead probes should be
used.
Unless a coaxial-style
probe is used, probes
should not be in direct
contact with a metallic
object, as that will impact
the signal.
Ultrasonic Aqueous liquids,
chemicals, silos
containing dry products
such as pellets, grains,
or powders,
Virtually
maintenance free
turbulence can be
tolerated but
foaming will often
damp out the
return echo.
Non-
contacting
temperature to
around 158 °F (70 °C)
and pressure to 43
psig (3 bar).
Obstruction(pipe ,
agitators) in tanks
need to be avoided.
Liquids which form heavy
vapours, steam, or vapor
layers should be avoided
(use a radar transmitter in
these instances).
No vacuum applications.
Radiometric Highly corrosive
Liquids, viscous, toxic
dirty liquids.
No maintenance Can tolerate foam,
turbulence, mist,
heavy vapour
density.
Non
contacting
Low radioactivity is
required.
Measurement is
independent of pressure,
temperature and product
aggressiveness
Acoustic phased
array
solid materials Low maintenance Cannot tolerate
foam , turbulence.
Non
contacting
Avoid obstacles like
Inlets
Internal structures
Ladders
Support beams
Thick roofs
incorrect mounting
location may result in
erroneous measurements
or loss of performance.
Microwave
barrier
Bulk Solid materials maintenance free Cannot tolerate
foam , turbulence.
Non
contacting
Soliwave is suitable
as point level switch
for controlling and
counting all types of
bulk solids.
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36. References
• https://www.endress.com/en/field-instruments-overview/level-
measurement
• file:///C:/Users/998590/Downloads/FA00001F00EN1613.pdf
• The Engineer’s Guide to Level Measurement 2019 EDITION
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