The document discusses using ultrasonic spectroscopy to monitor real-time wort Plato and yeast levels during the beer brewing process. It describes how the Rhosonics Model 9100 can monitor concentrations throughout various stages, including wort preparation, boiling, fermentation, and bottling. This allows brewers to optimize efficiency, consistency, and quality by accurately tracking parameters like original gravity, extract, and alcohol levels.

1. Real-time Wort Plato and yeastReal-time Wort Plato and yeast
Monitoring Systems forMonitoring Systems for
» Beer breweriesBeer breweries

2. In modern beer brewing, much of the original
craftsmanship is being taken over by fully automated
installations. Where product quality was often
maintained by skilled personnel and where the brewing
process, in many cases, was controlled by visual checks
and experience, modern breweries ask for automated
and repeatable instrumentation to keep track of product
flows, both quantitatively and qualitatively.
This application note explains how ultrasound in general
and the Rhosonics Model 9100 in particular is used to
monitor the product quality and to take over many tasks
that formerly had to be done by human intervention.
The production of beer falls apart into 5 major steps,
i.e. malting, brewing, fermentation, ripening and
bottling. Malting is the step, during which barley is
germinated. It is a highly specialized profession, not
very often done at the brewery itself.
Many breweries produce stronger beer than they bottle,
obviously to utilize their equipment more efficiently and
to reduce the required storage capacity for ripening.
This so-called high-gravity beer is blended with water to
obtain the desired strength just prior to bottling.
Since many years, the government has understood the
value of beer as a source of income. Excise duty is one
of the main reason to measure the concentration of
wort. The duties are simply determined by measuring
density, and then multiplying the difference in density
with pure water with the total amount of produced
wort. This asks for both accurate flow and density
meters.
Plato and Yeast Monitoring
using Hybrid Ultrasonic Spectroscopy
The amount of sugars in water, expressed in weight
percents, has a direct relation with the density of
the fluid. This weight percentage, or grams of solids
per 100 grams of product, is commonly known as
Wort Plato Index. One degree Plato equals 1 mass
percent of dissolved solids (i.e. sugars). Most beers
have a wort Plato index of between 10 and 20 °P.
When wort is 20 °P, its density is 1.08096 kg/l. A
change of 0.1 °P represents a change of only .00045,
that can be measured quite accurately by the aid of
densitometers. These traditional instruments look
like thermometers, with a calibrated scale. The
lighter the wort is, the more the meter is immersed.
A calibrated scale and a built-in thermometer,
together with conversion tables to normalize the
reading to 20°C, make an accurate reading possible.
During fermentation, the sugars are partly converted
into alcohol and carbon dioxide. The end product
hence contains alcohol, carbon dioxide and
unchanged extract. An important factor for the
quality of the beer is the alcohol, that can be
expressed in terms of volumetric or in weight
percentage. But an important part of the extract
remains unchanged, so the brew master must also be
aware of this value.
Due to the fact that alcohol is lighter than water, the
density of the beer cannot be used to determine both
alcohol and extract value. But since the density of
the wort is already measured before it became beer
and the density of the ready beer can be measured,
the extract as well as the alcohol content can be
accurately determined, using tables or equations.

3. As a result, many, for outsiders quite confusing terms
are used to describe the quality of the beer. The density
of wort, for instance, is often referred to as “original
gravity”, since this value is used in a later stage to
determine alcohol and extract of the finished beer. The
original gravity can, as explained earlier, be directly
related to the Plato index or “Extract” value. But the
density of beer is no longer a direct measure for extract
nor to alcohol, and is therefore commonly converted to
the “Apparent Extract” value. The “Real Extract” value
is the amount of extract in the finished beer, that has
not been converted to alcohol.
The original gravity or wort Plato index is a very
important parameter for the brewer. As we have seen,
the brewer can determine the alcohol and real extract
value in the finished beer, using the original gravity and
the apparent extract value.
But many brewers deliberately make stronger beer than
they anticipate to deliver to their customers. In this
case, the beer is diluted with water to obtain the
desired alcohol and extract value.
In the next episode, some applications will be discussed,
where the Rhosonics Model 9100 is applied to monitor
one or more of the discussed parameters.
Applications
There are numerous applications where the
Rhosonics ultrasonic analyzer is a very handsome tool
for optimizing the process or for saving production
costs.
Wort preparation
For most breweries the production starts with the
preparation of the wort. A batter is made of the malt
by mixing it with water. The starch, one of the main
components of the malt is then converted into
sugars, by an enzyme, which is naturally present in
barley.
Common purpose is to obtain an extract, that is rich
of different types of sugars, like maltose and
dextrose. A general characteristic is that during this
process the concentration of extract in the brewing
water becomes higher. When the concentration has
reached its target value, the non-soluble particles
are removed in the Clarification tank
Clarification tank
When the brewing process has come to an end, the
mash tun is being emptied and the wort needs to be
filtered in a pan, that is called “lautertun”.
The solids in the wort form the filter bed in the
lauter tun. The bottom of this tun has many small
openings, and while the wort is flowing away through
these small openings, it is pumped back into the
lauter tun at the top. During this first stage of the
process, the wort Plato value is quite constant,
typically 18 ºP for pilsener. While the process goes
on, the turbidity of the wort is improving gradually,
because the solids deposit on the filter bed, bind
formed by the solid materials themselves. At the end
of this stage, taking about an hour, the wort is
sufficiently cleared and then pumped to the wort
coppers for boiling.
When the wort is almost gone, brewing water is
being sprayed on the filter bed to dissolve and the
last remaining of extract. This process is known as
sparging. The Plato content then slowly drops from
the original value of 18 ºPlato down to a value of 3
ºPlato, where the flow to the wort copper is
interrupted. The very weak wort that then exits the
lauter tun is fed to a buffer tank, where it will be
stored and used as sparging water for the next batch
of wort to be cleared. 1,5 ºPlato. When too much
water is added, the wort is diluted too much. All
excess water has to be evaporated during the boiling
of the wort, taking a lot of energy.

4. The Rhosonics analyzer model 9100 is used to monitor
the outlet of the lautertun, in order to follow the
gradual decrease in concentration of the wort.
Considerable savings are realized, since the brewer is
now able to finalize the process at the right moment,
thus saving wort, as well as brewing water. The
Rhosonics Model 9100 has been calibrated for this
product in the range of 0 to 25 °Plato, at a temperature
range that is normal to the process, i.e. 40 to 65 °C.
The sensor is located in the actual process line and can
stay there without the need for recalibration, as it is
virtually drift-free. Whenever the lautertun is cleaned
by means of CIP, the sensor benefits from this. The
strong acids and alkali’s, as well as the boiling hot
temperatures do not damage or age the sensor in any
way. These features make the Model 9100 the ideal tool
to optimize this part. The automatic control also
prevents the formation of esters, due to excess dilution
with oxygen-rich sparging water. These esters cause a
bad taste to the end product.
Wort kettle
Starting with the wort preparation, the efficiency of the
brewing process increases considerably when the brewer
knows exactly when the wort Plato index has reached
the desired value. By reducing the production time,
both energy consumption and product quality improve.
Since the aseptic sensor of Rhosonics can handle
temperatures up to 150°C and withstands temperature
shocks from cold to hot and vice versa, the Model 9100
is the ideal instrument for measuring the extract value
in the wort boiler.
In the wort kettle, the incoming wort from the lauter
tun is gently preheated from a temperature of 75 °C up
to the boiling point of 100 °C in about one hour. The
most commonly used heating system is an internal
steam-heated percolator.
Once the preheating duty of raising the wort to the
boiling point is complete, the evaporation duty can
commence. Heated by steam, the percolator induces a
convectional flow, causing a natural circulation of the
wort in the kettle and also along the Rhosonics sensor.
Once the heated and boiling wort in the centre of the
kettle reaches the surface, evaporation of water takes
place. From there, the wort is naturally flowing away
radially and then to the bottom along the wall of the
kettle. It is at this point that the indication of the
sensor becomes important. The most important reading
of the analyzer is at the end of the boil, where some 5%
of the water has been evaporated.,
Boiling the wort has many purposes, like sterilizing
the wort, coagulation of proteins and extracting
bitterness from the hops. Also, hop is added to
improve both taste and tenability of the end-product.
The most important function however is to evaporate
water which in turn increases the Plato index of the
wort. To maximize plant productivity, each brew
should be as large as possible and brews should be
put through as fast as possible by maximizing heat
transfer and evaporation rate.
The usual method to control this process is by
controlling the amount of energy and time. Because
many factors have an influence on the boiling
process, and consequently affect the final Plato
index of the wort, it is important to measure the
strength of the wort, especially at the end of the
boiling process.
Cold Wort
In modern beer brewing, it is very important to
obtain a good product balance. Information about
the used amount of material and the amount of wort
and beer produced, gives a better means of
controlling and reducing the amount of product
losses in the brewery. An import product is the cold
wort, just prior to fermentation. Because the wort
Plato index is not constant in time, as well as the
flow rate, it is important to measure both and weigh
the Plato Index with the flow rate, in order to get
the average wort Plato Index of the wort that is
going to be fermented. The wort is usually 7 to 15
°C, depending on the process. The Model 9100 can
be best implemented after the cooler, but before the
air injection point, since air bubbles scatter the
ultrasound waves. Although Rhosonics has developed
special software to maintain its accuracy during the
presence of air bubbles, the continuous presence of
air bubbles prevents ultrasound transmission and will
make the measurement impossible. Accuracy of the
Rhosonics in wort is as high as 0.04 °P, this is equal
to +/- 0.00017 kg/l in terms of original gravity.

5. Fermentation
When the fermentation process starts, the sugar in the
wort is partly converted into alcohol and carbon
dioxide. Depending on the fermentation process, the
wort is cooled from boiling temperature to about 6 to
15°C and mixed with air and yeast. The air is introduced
to start the fermentation process, during which the
extract is partly converted into alcohol and carbon
dioxide. The main fermentation takes about 6 to 12
days, for specific types of fermentation even much
shorter. The yeast is removed from the product, and is
used for many other purposes. Measurement is only
possible when the surface of the sensor is kept free of
air. In this application, the sound speed increases, just
as if the amount of sugar increases. This is a basic
difference with density meters, since the density is
positively affected by extract and negatively by alcohol.
This is the reason that the density of beer is converted
to “apparent extract”. With ultrasound, the sound speed
change per °P is about 4 m/s, whereas the sound speed
change with alcohol is about 8 to 11 m/s. So, during
fermentation the sound speed increases. This is a great
advantage, because when the starting sound speed is
known, the alcohol and real extract value can be
derived from the beginning and the sound speed at the
moment of interest.
From any type of beer, the real extract value and
alcohol percentage can be calculated by a combination
of density and ultrasound. Also a combination of
brixmeters (refractometers) and ultrasound can be used,
because these two measuring principles respond
differently to alcohol and extract.
Ripening
During the ripening process in storage tanks, the beer is
fermenting at a much slower rate. In this stage,
albumen and tanning deposit, thus improving the taste
of the beer. This can take, depending on the type of the
beer, 6 to 16 weeks. Meanwhile, the beer gets saturated
with carbon dioxide, enhancing the tenability of the
beer. When ripening is complete, the beer is filtered and
then ready for bottling.
Beer bottling
This brings us to the next application for the Model
9120, and that is the measurement of finished beer,
as a mixture of high gravity beer and water. In this
application, ultrasound offers the distinct advantage
over density meters that they are much more
sensitive to concentration changes and therefore
much more accurate. An average beer may have an
original gravity of 11.5 °Plato and 4 % alc. The
density at 0 °C is 1.0094. The sound speed of this
beer is about 60 m/s higher than of water. Since the
accuracy of the Model 9120 is better than 0.05 m/s,
the original gravity in blending applications can be
measured down to 0.01 °P. Imagine a density meter
that matches this precision; it would require
accuracy down to 0.00001. Only laboratory
instruments can match that precision.
It must be said, that the alcohol to extract ratio
must be fairly constant. If this is not the case, for
instance when different beer types are processed
there is a possibility to remotely switch the Model
9100 to a different recipe. When the best accuracy is
required or when all individual components have to
be controlled, the addition of a density (U-tube)
meter is necessary. When CO2 is present, the
addition of a CO2 analyzer is also required. The
results of these analyzers are fed into a computer,
that uses a special program to calculate all required
parameters: extract, alcohol and original gravity and
CO2.

6. Filtration
Another very important application, if not the most
important of all, is the monitoring of the beer during
start-up and during the end of a production cycle.
Prior to each production cycle, the filter installation is
filled with water. During start-up, the water must be
flushed out by means of the beer. During this process,
the concentration is gradually increasing from zero to
the desired value. For the brewer, it is important to
know when the “interface” passes by. This interface is
not a clearly marked separation between the water an
the beer, but there is a gradual increase of the beer
concentration. When the beer has the desired original
gravity or “Stammwuerze”, as it is called in Germany,
valves are closed and opened to direct the beer to
storage tanks prior to the final bottling. At the end of
the production interval, the reverse of the above
described procedure takes place. When the original
gravity drops below a critical value, the valves are
switches to redirect the flow to a different target.
Where the brewer previously had to switch valves
manually, based on pre-determined time intervals,
considerable savings are realized, normally in the order
of magnitude between 10 an 25 hectoliters per charge.
Major features of Models 9100 and 9120
The Models 9100 and 9120 consists of 3 major
components: a sensor, a process interface and a user
interface.
The most important part, the sensor is located
directly in the product stream. This is made possible
by a specially developed Tuchenhagen Varivent©
housing, that has two openings for the installation of
various instruments. Only one opening is used by the
Rhosonics analyzer, the other opening is closed with
a blind flange.
The second most important part is the process
interface. This part takes care of processing all
signals going to and coming from the sensor. The
process interface also translates the sound
parameters and the temperature into a
concentration. It features a direct link with a PC.
The third component is the user interface, that
enables the user to locally monitor the analyzer and
change recipes as well as ranging the recorder
outputs and the alarms.
Remote computer control
The Windows95 application software enables to
completely control the unit remotely. This is useful in
the following situations:
Suppose that several beer types flow through one
pipe. Whenever the product is changed, the Model
9100 may require switching of the recipe. By means
of the remote computer this is now done
automatically, together with all other process
settings that are required for the product change.
Next, all measured data are automatically stored by
the program and can be visualized upon request. An
additional advantage is that the measured values do
not lose any accuracy and can be processed more
easy than with analog transportation.
Finally, in multi-parameter systems, the
measurements are easily combined to solve complex
relationships between the measured parameters and
the data of interest, such as original gravity, extract,
alcohol and CO2 content.
The Plato analyzer of the Future

7. Worldwide distribution.
Please check our website for details.
v1.6
The mission of Rhosonics Analytical is to provide
solutions for In-line concentration analysis of
virtually all existing process liquids, including
electrolytes, emulsions, suspensions and slurries.
For almost two decades, Rhosonics Analytical has
been focusing on the development and
employment of high-performance ultrasonic
technologies for in-line liquid concentration
analyzers and non-destructive testing of
materials.
Our products
 In-line concentration analyzers for virtually
all existing process liquids, including
solutions, electrolytes, emulsions,
suspensions, solids and slurries.
 Piezo composite transducers for Ultrasonic
NDT (Non-Destructive Testing) for new
inspection methods, including ToFD and
Phased Array.
The Solution Specialist
Rhosonics Analytical is The Solution Specialist
for the design, production and supply of
ultrasonic in-line process analyzers for liquids and
slurries in any industry world wide.
The Solution Specialist Contact
AAVOS International bvba
Sparkevaardekenstraat 3
8600 Diksmuide
Belgium
Tel : +32 (0)51 69 78 15
Fax: +32 (0)51 69 78 17
Info@aavos.be
www.aavos.be
The Solution Specialist

8. 9100 Series
Ultrasonic Beer Analyzers
Ultrasonic concentration
analyzers for modern breweries
Model 9110 Wort Analyzer
Dedicated to measuring wort extract concentration
only. The new non-linear regression provides
accurate inline analysis regardless of temperature,
in the complete range of up to 25 ºP and above.
Main applications:
 Mash Tun
 Wort clearing
 Boiling wort
 Cold Wort
Model 9120 Beer Plato Analyzer
Dedicated for measuring the original gravity of beer,
regardless of the type of beer
Main applications:
 High Gravity Beer blending
 Water pre- and after runs
Model 9170 Beer & Slurry
Measures the suspended solids in addition to wort
Plato in beer. Provides an TSS, i.e. yeast percentage,
ranging from 100 mg/l up to 400 g/l
Main applications:
 Yeast concentration in green beer
 Yeast slurry concentration
Model 9175 COD
Influent analyzer, providing inline COD
analysis of waste water.
The Beer Plato Analyzer of the Future
Introducing Series 9100
The 9100 series analyzers provide in-situ, drift free
process information throughout the beer brewing
process. Thanks to almost two decades of intensive
research and experience in breweries, Rhosonics
Analytical is capable of offering analyzers which meet
the extremely high demands of modern beer brewing.
Specific hybrid sensor technology has been developed
to provide added functions, like the measurement of
suspended solids, while improving stability in
processes under non-ideal conditions.
Already in 1993, Rhosonics was the first to introduce
a Plato Analyzer, which could cope with suspended
CO2
, and was able to maintain a stable concentration
output even at varying temperatures.
The 9100 Series Analyzers of Rhosonics Analytical,
combine these advantages with modern sensor
technology, to provide accurate, long lasting and drift
free analysis of brewing products.

9. Worldwide distribution.
Please check our website for details.
v1.6
The mission of Rhosonics Analytical is to provide
solutions for In-line concentration analysis of
virtually all existing process liquids, including
electrolytes, emulsions, suspensions and slurries.
For almost two decades, Rhosonics Analytical has
been focusing on the development and
employment of high-performance ultrasonic
technologies for in-line liquid concentration
analyzers and non-destructive testing of
materials.
Our products
 In-line concentration analyzers for virtually
all existing process liquids, including
solutions, electrolytes, emulsions,
suspensions, solids and slurries.
 Piezo composite transducers for Ultrasonic
NDT (Non-Destructive Testing) for new
inspection methods, including ToFD and
Phased Array.
The Solution Specialist
Rhosonics Analytical is The Solution Specialist
for the design, production and supply of
ultrasonic in-line process analyzers for liquids and
slurries in any industry world wide.
Contact & DistributorsThe Solution Specialist
Info@aavos.be
www.aavos.be
Tel: +32 (0)51 69 78 15
Fax: +32 (0)51 69 78 17
AAVOS International bvba
Sparkevaardekenstraat 3
8600 Diksmuide
Belgium
The Solution Specialist

12. PLATO METER F43
PRODUCT INFORMATION
CONTINUOUS IN-LINE MONITORING AND PROCESS CONTROL

13. INTRODUCTION
Rhosonics introduces the Plato Meter F43. This
new generation instrument can be used in the
brewing process for wort extract concentration
measurement and is suitable for generally all
types of beers. The Plato Meter F43 provides
highly accurate measurements up to 0.01 °Plato
with a range up to 40 °Plato and above. This
instrument is the solution for modern breweries
who are searching for a user-friendly, all-in-one,
reliable, robust, real-time and in-line device to
monitor their brewing processes.
DESCRIPTION
The Plato Meter F43 measures the °Plato by
means of the sound velocity. Unlike other
measuring systems, the instrument does not
require a bypass installation. The sensor,
evaluation unit and control panel are all
combined and integrated in the compact design
of the instrument. Hence, there are no complex
configurations needed. Simplicity has been a
key topic in the development. This resulted in
very user-friendly software and a simplified
calibration procedure. The Plato Meter F43
provides a HART/4-20 mA or RS232 output
which can be used for communication with the
control room.
FEATURES AND BENEFITS
The Plato Meter F43 offers:
• the highest level of accuracy (+/- 0.01 °Plato)
• a simple configuration and operation
• a robust and compact all-in-one system
• durable housing materials for a long lifespan
• no moving parts, virtually no maintenance
• an easy in-line installation into pipelines
• aseptic and bypass-free installation
• intelligent software for °Plato calculations
• temperature compensation by Pt100 sensor
• reproducible measuring results
• continuous data & system logging
• communication via HART/4-20 mA or RS232
INSTALLATION AND APPLICATION
The Plato Meter F43 can be installed in the pipe
via a VARIVENT™ connection where the sensor
is clamped into for direct in-line measurements.
The instrument can be used in various stages of
the brewing process. Some of the typical
applications are shown in the figure below.
1. mash filter outlet pipe
2. wort boiler circulation pipe
3. wort cooler outlet pipe
The Plato Meter F43 is installed in a pipe by means of a
VARIVENT™ connection.
0
1
.
2
.
3
.
Mash filter
/ lauter tun
Wort
Boiler
Wortcooler
Plato Meter F43 for highly accurate °Plato measurements

14. ULTRASONIC MEASUREMENT
The Plato Meter F43 makes use of an ultrasonic
sound velocity measurement. The sensor sends
and receives the ultrasonic signal which is
traveling through the liquid and returns to the
sensor by means of reflection. The total time of
flight through the liquid is measured and from
the total travel distance and this time of flight
the sound velocity is calculated. The sound
velocity is translated into the requested
measurement parameter °Plato by a unique
polynomial which is created in the Rhosonics
laboratory. The speed of sound is strongly
influenced by the temperature and for this
reason also the temperature is measured by an
integrated Pt100 temperature sensor.
HOUSING DIMENSIONS
TECHNICAL DATA
208mm
304mm
Sound velocity
measurement
PERFORMANCE SPECIFICATIONS
Method:
Ultrasonic sound velocity & Pt100
temperature measurement
Measuring range: 0 - 40 °Plato
Readings: Original Gravity, °Plato
Accuracy: Up to 0.01 °Plato or 0.5% of reading
Decay time: 1 to 99 s (adjustable)
Display:
Monochrome display with RGB
backlight, behind glass cover
Operation: Push-buttons, HART, Computer
170mm
GENERAL SPECIFICATIONS
Process conditions
Pressure: max 16 bar
Temperature range: 0 °C to 110 °C (32 °F to 230 °F)
Wetted materials:
Ceramics Duplex 1.4462
Food Grade Sensor Parts
Electrical specifications
Power supply: 18 … 32 VDC, 8 Watt
Communication &
Output:
HART/4…20mA
or Modbus RTU/RS232
Data logging & fault
reporting:
Internal memory, via USB memory
stick
Cable entries: 3x M16X1.5, cable OD Ø 3-10 mm
Ambient conditions
Ambient
temperature:
-20 °C to +65 °C (-4 °F to 149 °F)
Humidity: < 95% at 40 °C (noncondensing)
Protection: IP68, NEMA 6P
Vibration:
Resistant to moderate / high
vibration of pumps
Housing dimensions and weight
Weight: Approx. 6.4 – 6.8 kg
Housing materials: Coated stainless steel
Dimensions: 304 x 208 x 170 (L x W x H in mm)
Process connection: VARIVENT™ pipe connection
© 2017 Rhosonics Analytical B.V. | Specifications are subject to change without notice.

15. MISSION STATEMENT
Rhosonics is based in the Netherlands near
Amsterdam. We design, produce and supply
state-of-the-art measuring instruments for
virtually any industry. The company cooperates
with partners worldwide to offer the best
technology solutions. We use craftmanship,
capability and creativity to create measurement
beyond limits.
CONTACT US
© 2017 Rhosonics Analytical B.V. | All rights reserved. | Brochure Plato Meter F43.
We work with a global network of specialized distributors. Please check our website for distributors in your specific region.
Headquarters Distributors
About us
We proudly meet the requirements
for the ISO9001 standard since 2010.
Info@aavos.be
www.aavos.be
AAVOS International bvba
Sparkevaardekenstraat 3
8600 Diksmuide
Belgium
Tel : +32 (0)51 69 78 15
Fax: +32 (0)51 69 78 17