Not clear on what water activity is? Check out our other posts on water activity here!
Water activity affects a wide range of products from pharmaceuticals to foods, here we take a brief look at five typical applications where water activity measurements are used.
Remember water activity affects biological, chemical and physical properties of products.
Application 1 – Food
Water activity is critical in food production, reducing water activity reduces the available moisture for spoilage organisms to utilise as such low Aw can limit or prevent growth and spoilage.
Aw is often used to screen raw ingredients or end products to confirm that they are within tolerance. Aw measurements only take a few minutes and can therefore provide immediate feedback. This can save time, money and prevent health risks or product spoilage.
Aw can be used as an excellent indicator of shelf life. Once a production process has been fine tuned to deliver products with suitable shelf-life, online aw measurements can confirm production consistency.
Classic methods to control Aw in food are listed below.
Application 2 – Paper
Water activity or %equilibrium relative humidity in paper may not be your first thought, but the impact of poor or changing ERH in paper can be very costly. Changes in ERH can cause paper to curl or lead to increased static both of which can cause paper jams. For an industrial printing company this can lead to costly downtime. ERH also affects the binding of inks, drying times and ultimately spoilage by moulds and fungi.
Application 3 – Pharmaceutical Products
Drug production and storage is one of the most highly regulated manufacturing sectors. All stages of drug production, storage and delivery rely on critical control of many factors including water activity. Most drugs must be stored in stable conditions hence the advanced moisture impermeable packaging used. Aw readings as well as humidity monitoring and control are utilised to ensure free water is maintained within tolerance.
Application 4 – Seed preservation and storage
Seeds present an interesting challenge, if Aw is too low the seeds quickly become non viable, where as too high and they may germinate or suffer spoilage through mould or fungal growth. One of the most critical seed preservation projects is the Millennium Seed Bank project. More details about how Rotronic AW meters were used is avaialble on the Kew Gardens website
Application 5 – Soaps and powders
Finally we come to good old washing powder, even with powders and liquids now packed into clever tablets and pods Aw remains critical. The materials must be stored in a way that ensures safe delivery to the customer but can be released once in contact with water in your washing machine. The science of behind the latest washing powders and liquids relies heavily on the measurement and conrtol of water activity and %ERH!
Hopefully this brief in site into how water activity affects so many day to day products has been useful. For more information visit our website or contact us to discuss!
Campbell Scientific (CSC) are an ISO 9001 certified company who are a leading manufacturer in a variety of applications related to weather, water, energy, gas flux and turbulence, infrastructure, and soil. Campbell Scientific, are committed to satisfying the instrumentation needs of their customers, and are internationally recognised in the measurement and control industry for producing accurate and dependable instruments
CSC systems are acclaimed for their dependability, which they demonstrate even in the most extreme weather climates. Their attributes include wide operating ranges, low energy usage, many communications options, and the flexibility to support a wide variety of measurement and control applications. Applications include, agriculture, air quality, fire warning, water quality, weather and climate recording, structural monitoring, Geo-technical monitoring and mining.
Rotronic and CSC have been business partners for many years, CSC uses the standard Rotronic meteo probe in many applications. Recently CSC installed the probe in a network of Road Weather Information Systems in Kelowna, British Columbia. CSC selected the probe because of its reliability, ease of use and accuracy. The HC2A-S3 is also highly regarded for its ability to function in extreme temperatures, this makes it good for the Canadian climate, and a perfect complement to Campbell Scientific systems.
” We value the Rotronic HC2A-S3 probe for its ability to function at extreme temperatures.” Mike Ryder Campbell Scientific, Canada
For more information on the latest HC2A-S click here ,or for any of our products please visit theRotronicwebsite.
For a long time, people have tried to predict weather conditions using the hydrologic climate cycle.In the early 1920’s scientists were able to compile a six hour forecast, back then it took six weeks to analyse weather data collected at only two points in Europe and calculate, by hand, a useful illustrative model. Today, supercomputers are used to predict the weather for a period of several weeks. The complex modelling programs require several million data points for parameters such as temperature, humidity, pressure, vertical & horizontal wind velocity with time stamps and absolute coordinates. To create a correlation between the data and the environment, scientists “slice” the atmosphere virtually into smaller horizontal &vertical parts—this process is called discretisation. It is more useful to compute the chronological change of the parameters using this model.
Clockwise from top left: Map of the average temperature over 30 years. .Weather station on Mount Vesuvius. .Water cycle summary
Meteorological events that are too “small” such as a single thunderhead, layer clouds or smaller turbulence’s will be parameterised through variables. This parameterisation is a science of its own that aims to reduce uncertainties as best as possible. Every forecast calculation starts with the current weather conditions. The quality of this input is crucial for the accuracy of the final forecast. Meteorologists link the forecast of yesterday’s weather with the actual measured parameters. Only large data centres are capable of computing this data assimilation. The overall result is a best possible calculation basis predict the weather for the next day. If this groundwork is flawed the forecast may be incorrect. For example, it could report rain at the wrong location. Today’s meteorological mathematicians also take parameters into account that change extremely slowly compared to the other factors. Growth and the reduction of polar ice, or the temperature of the oceans are summarised as boundary values. After a model is run using all the available data, meteorologists process and customise reports for a wide range of target groups such as public authorities, flight control centres, energy producers, industries and many more. These reports also include specific weather warnings.
Why the need to measure humidity?
Atmosphere composition diagram
As described above, the daily weather forecast relies on the precise measurement of weather parameters. The science of numerical weather prediction aims to describe the daily hydrologic cycle in numbers. Humidity plays an important role. Typically, data errors will multiply during calculations. Humidity values influence weather calculations e.g. through the water vapour balance equation— this formula expresses the influence of humidity through rain & condensation, and vice versa. Incorrect measurement or incomplete humidity data directly leads to wrong predictions of a huge number of weather phenomena such as the condensation altitude of clouds, locations of hyetal regions, fog layers and storms. In 1999, incorrect data sent by a weather station in Nova Scotia, Canada led to a incorrect forecast for Hurricane Lothar two days before it hit Central Europe. Authorities were insufficiently prepared to alert people in time. The prediction of rain and snowfall is still challenging for meteorologists. Only more extensive networks of weather stations and enhanced mathematical models will reduce problems due to unknown factors.
Facts & Figures
7 inches is the diameter of the largest hailstone ever recorded.
Sukkur City in Pakistan is one of the most humid places in the world with
30 °C dew point & a felt air temperature of 65 °C.
A study showed that a small thunderstorm system holds more than 10 million tons of water.
No two weather patterns are completely alike.
Some weather models assimilate data obtained from more than 25,000 weather stations.
Rotronic has released launched our next generation server based Environmental Monitoring System (RMS), but here we take a look at our traditional system that is still fully supported and widely used in the pharmaceutical industry and beyond.
The German pharmaceutical manufacturer Dr. R. Pfleger GmbH requires specialist cleanroom environments for many areas of production and development. It is vital for the company to monitor and verify pressure conditions as well as humidity and temperature data in its cleanrooms. To meet this need,the company uses validated Rotronic data loggers from the Hygrolog HL-NT series.
Together with theRotronicvalidated HW4 monitoring software, these data loggers deliver important information on the environments that have an influence on the production of pharmaceutical products.
The Rotronic monitoring system has stood the test of time in the market over many years and undergone continuous development. The HW4 software forms the heart of the system. It visualises and saves all data, configurations and user events and also triggers alarms. Its audit trail logs all data and activities in compliance with FDA21 CFR Part 11 and GAMP5. Rotronic calibrated, qualified and validated Dr. R. Pfleger GmbH’s monitoring system according to GMP requirements.
Overall control and regulation
The management system forms the basis for operation, monitoring and control of the technical facilities as well as for data and message management. Apart from the technical installations, the validated clean room monitoring system is implemented
directly in FIS (OPC interface).
HygroLog HL-NT data logger – The central acquisition unit is a HygroLog-HL-NT data logger. It provides digital inputs for HygroClip humidity and temperature probes as well as Pt100 and 4…20 mA devices.
The data logger is also equipped with a memory card which not only stores the measurement of data but also all the events in the instrument itself.
The digital HygroClip2 climate probes provide class leading precision and long-term stability. All calibration and adjustment data is stored internally. Their standard accuracy ex works is ±0.8 %rh and ±0.1 K, for more demanding tasks, sensors with an accuracy of ±0.5 %rh can be supplied.
Sophisticated Software – The HW4 software saves the measurement data, alarms and events in a protected binary format. Any manipulations are detected and the data record is then marked as corrupt. Instruments are organised in groups and shown in the room layout. Colour changes make alarms and disturbances easy to recognise.
Evaluation and archiving
A data file is created for every measuring point. Mean Kinetic Temperature values are calculated from this raw data. The evaluation also contains alarm times and deviations and is presented in the form of a table with statistical values. Thanks to the high level of integration of the hardware in HW4, virtually all Rotronic instruments can be implemented in the existing monitoring system.
The monitoring system implemented by Rotronic offers a consistent solution, since all main and secondary installations and the monitoring system itself are integrated in the FIS management system, they can be monitored and controlled via a central software platform.
Dr. R. Pfleger GmbH
Medium-sized pharmaceutical company located in the city of Bamberg,
The company is entirely owned by the Doktor Robert Pfleger-Foundation
The company now markets over 30 medicinal products
Primary focus on urological, gynaecological, and dermatological indication
For more information on any of our products please visit the Rotronic website.
Switzerland has around a dozen duty-free warehouses. These warehouses are transit zones for the storage of goods whose main advantages are the temporary suspension of customs law and taxes. They benefit not only from a location in the heart of Europe, but also from legal and political stability. The company Ports Francs et Entrepôts de Genève SA, is based in La Praille, where it manages a floor space of 150 000 m², half of which under the Swiss customs regime (duty-free).
To ensure it is able to meet high standards in quality and security, Ports Francs opened a new warehouse in 2014. It was specially designed to store valuable products in accordance with the requirements of insurers. To establish the necessary climatic conditions, RotronicHF1temperature and humidity transmitters were installed to enable control of the optimum storage climate.
Hygroflex Transmitters HF1 Series
1000 commercial premises in La Praille
There are currently 10 duty-free warehouses in Switzerland. Duty-free warehouses are usually located near national borders and airports. In contrast to most other countries, there is no time limit for storage in Swiss duty-free warehouses for goods not stemming from Switzerland. In 1888 the canton parliament approved the establishment of the operating company Ports Francs de Genève SA, which was later renamed to Ports Francs et Entrepôtsde Genève (PFEG).
Ports Francs et Entrepôtsde Genève
There are almost 1000 commercial premises of all sizes available in la Praille. The type of goods stored in duty-free warehouses has changed immensely over the years. The
strong development in the art and wine market has given rise to special security and quality requirements concerning,in the first instance, storage conditions (temperature, humidity and vibrations). The new warehouse building, designed in collaboration with specialised contractors, was inaugurated in 2014. The building, which serves mainly to store valuables such as antiques, works of art and wine, is the result of close co-operation between various specialists in security issues, insurance, energy and architecture as well as the end users. The numerous elements listed in the requirement specification included the critical details relating to climatic conditions (temperature and humidity) in the building’s storage rooms.
Like in our wine cellars
To ensure a high standard of quality and security, Ports Francs et Entrepôts de Genève SA approached the Zurich-based company Rotronic AG in Bassersdorf. “We need precise and stable measuring instruments,” says technical director Marc Golay. The building concerned is equipped not only with a ventilation and air-conditioning system (humidity and temperature), but also with a central building management system utilising the concepts of MSR (measuring, control and regulation). The building is divided into two large parts. The first is for storage of wine in accordance with applicable regulations (70% humidity, 13°C), as in the cellars of our forefathers. The second part is reserved for sensitive and valuable goods, primarily paintings (55% humidity, 21°C). “Since it was one of the main aspects of the building concept, we also wanted to have the possibility to trace the climatic conditions during storage.” This very functional location enables arrival of the goods by road with a loading platform and direct access to the premises. Equipment rooms, escape routes, freight elevators, elevators and sanitary facilities round off the building. “We wanted a system able to maintain a constant level of humidity and a constant temperature everywhere and at any time of the year. To ensure control and logging of these parameters, we opted for the measuring instruments from Rotronic”, adds Marc Golay.
Depending on the storage area of the goods, it is not always easy to check whether ventilation and air replacement are working effectively everywhere. The solution was to utilise 227 Rotronic HF1 transmitters within the complete premises. The instruments are monitored remotely by the MSR system from the Geneva manufacturers EnerBat – a specialist in the technical and energy monitoring in buildings – the system checks daily that the temperature and humidity requirements are being met. Since the building was designed to guarantee the best storage conditions, it does not have any windows so that the climatic conditions can be kept as stable as possible. To improve security for protection and prevention of fires, all stores are equipped with a common, dedicated gas extinguishing system.
The importance of using measuring equipment
Why was Rotronic preferred over other companies?
“It is a company with an excellent reputation that takes action immediately when necessary. It is extremely important that the probes work reliably and accurately as they deliver all the information on the climatic conditions in the building,” explains the technical director. Thus the importance of the measurements. The wall mount T/rh probes for the duty-free warehouse were fastened to the walls at a height of about 150 cm from the floor. They enable control of the temperature and humidity in the room air and emit a warning signal when limits are exceeded. The probes are also connected to the wider systems via analogue and digital outputs and finally integrated in a Scada monitoring system. “We decided to use the products from Rotronic because they were the best value for money,” says Fabien Caradot from Elitec. “There were of course other possibilities, but at the same price Rotronic scored higher with its HF1 product range in terms of quality, reliability of the material, technical support and calibration.” Elitec, which originally worked in the manufacture of electrical switchboards, today employs around 20 people and rounds off its portfolio of services with the fields of building automation, home automation and various inspection services such as technical and schematic analyses.
The Probes used the get the perfect temperature and Air humidity for Ports France et Entrepôts de Genève SA
260 Main HF135-AB1X Probe (227 installed, the rest are reserved)
22 Probes 9 Wall and duct mount probes) in the logistics hall of CICR
2 Wall mount T/rF probes and 1 duct mount T/rF probe in the archives of CICR
3 Duct mount probes in the red cross museum
1 Ventilated outdoor probe for the Swissquote building in Gland
JOWA AG Pasta has been the largest manufacturer of pasta products in Switzerland since it was founded in 1931. It is important for the company that its production operations run smoothly and meet strict quality standards.
Precision temperature and humidity probes from Rotronic are used to measure the climates in the factory’s six production lines, which predominantly manufacture dried pasta for the retailers such as Migros (Switzerland’s largest retailer). As a testament to the quality of Rotronic probes some units are over 15 years old and are still performing as required having only undergone routine calibration and adjustment to ensure that they provide consistently accurate accurate data.
JOWA AG manufactures 18,000 tonnes of pasta per year and is thus the largest pasta producer in Switzerland!
The pasta market is highly competitive and food legislation strict. It is therefore all the more important that the pasta is produced in the finest quality without production stoppages and rejects. The drying process plays a key role in the production of dried pasta and is therefore accorded top priority at JOWA. In order to control the climates optimally, temperature and humidity probes from Rotronic are used in the production lines. To preserve the food for a long shelf life and prevent mould and negative microbiological processes, the pasta is dried to a very specific level. Over drying wastes time, energy and produces a poorer quality product, under drying reduces shelf life and risks spoilage. Humidity and temperatures therefore need to be monitored closely during production. Legislation in Switzerland states that pasta products may not contain more than 13 percent water.
High Demands on Probe Accuracy
JOWA has been manufacturing pasta at its site in Buchs AG since 1963. The requirements of food standards, law and customers are rising continuously.
Oliver Höfler, head of the JOWA AG sites Pasta Buchs & Mühle Wildegg, comments:
“Every single production step needs to be traceable in ever more detail, down to each single packet of spaghetti. The temperature and humidity of each production step must be recorded exactly.”
If unwanted temperature and humidity variations were to occur in the pasta, this could lead to quality defects such as crumbling. The pasta would then dry irregularly and break during cooking. For this reason a sample is taken of every product from the first three and last three pallets for quality assessment. The heads of the different departments evaluate the products daily according to various specified properties such as taste and appearance.
Oliver Höfler explains: “If we have to recall products from various stores, this means an enormous financial loss of several ten thousand francs and also a severe blow to the image of our products. A dissatisfied customer – that is something we cannot afford. For this reason it is essential that we are able to rely on the measuring accuracy of the Rotronic probes to 100 percent.”
In addition to this, samples need to be taken for analysis from ongoing production every four hours. “ We greatly appreciated the open and transparent collaboration with Rotronic.” Oliver Höfler, JOWA AG, Switzerland Migros dried pasta perfectly monitored. Rotronic I200 sensor, providing reliable service for more than 15 years.
Project Workflow: Good and Long-Term Planning
Planning calibration time is the key to success with humidity instruments. JOWA AG in Buchs stops production twice a year, two weeks in winter and two weeks in summer, in order to check all equipment and machinery and so maintain the high quality standards. Andreas Zülle, head of production, ensured that the 50 probes (both the I200 transmitters dating back to at least the year 2000 and the newer HygroFlex5 generation) were disconnected right at the start of the last inspection so that Marko Schulze, Rotronic’s qualification technician on site, could begin calibrating the measuring devices. All probes were also catalogued. Marko Schulze: “JOWA’s planning was ideal, I was able to check all probes and either get them back into shape or replace them, and then we still had enough time to test the newly adjusted probes.”
The HygroFlex5 series of transmitters connect to our entire range of HygroClip probes and offers analogue and digital outputs for any application.
HC2-S probe provides superb precision and state-of-the-art functionality, taking humidity and temperature measurement to a whole new level of accuracy < 0.8 %rh and < 0.1 K at 23 °C.
Also available with ATEX / Intrinsically safe certification.
Smooth implementation of the inspection and calibration procedure was important to Andreas Zülle: “After the calibration, our process specialists were able to start up the production lines again without problem.” Oliver Höfler adds: “We greatly appreciated the open and transparent collaboration with Rotronic, found Marko Schulze to be an extremely competent partner and are sure we will be able to carry out calibration of our instruments even more efficiently next time. They have now been catalogued in detail. On top of that, we can also check the probes during operation with the Hygropalm from Rotronic.” Both sides benefit from good planning and a good working relationship.
Some Interesting Facts about Jowa
JOWA Pasta has been producing dried pasta for more than 50 years
The durum wheat semolina needed for production comes from a mill in Wildegg that also belongs to JOWA.
A team of 46, working three shifts a day, ensure daily that high-quality raw materials are transformed into products at an optimum price-performance ratio .
JOWA employs a workforce of around 3,200 people and, with more than 140 apprentices and trainees, is the biggest training company in the Swiss bakery industry.
JOWA AG is the leading Swiss bakery and supplies its customers from the retail trade, convenience stores and food service sector daily with a wide range of products and individual service concepts.
Jowa produce buns, cream slices to pasta, ham croissants and braided bread, some even gluten-free – the bakery assortment goes far beyond the classical bakery range.
The service concepts are tailored specifically to the requirements of customers and extend from logistics and marketing to in-store production.
The tasty JOWA breads and pastries are very popular.
JOWA breads are served fresh on the table daily in every third Swiss household.
Uncomfortable situations like this need not arise. CO2 displays by Rotronic make it easy to measure air quality, and the results can be used to initiate the appropriate measures. In an enclosed room, some 25 to 35 cubic metres of fresh air per person per hour are needed, given normal activities. This ensures that the carbon dioxide (CO2 ) content remains below 1,000ppm (ppm = parts per million [value of the proportion of carbon dioxide in the air]), and that the volatile substances exuded by humans are extracted to a sufficient degree. By comparison, the CO2 concentration in outdoor air is around 400ppm. The CO2 concentration is a good indication of the quality of the air in a room. The consumption of air rises particularly quickly in meetings, with many people in small rooms. By the time we notice this productivity has already declined. A CO2 sensor is the answer here. Alfred Freitag, Sales Manager for Switzerland at Belimo Automation AG, points out that a meeting should be interrupted when the CO2 concentration reaches 1,200 ppm and the room should be ventilated. The CO2 content in the air then drops rapidly, and productivity increases again.
The right to good air
Every person has a right to healthy indoor air (WHO). In the case of workplaces, the labour laws require that air quality and room climate must not represent a health hazard for employees. In the private sector, there are no regulations, and the owner is responsible. However, the Swiss Cantonal building regulations require energy-efficient buildings. This requirement can be met only when the buildings are airtight. Consequently, free exchange of air is no longer possible. Martin Bänninger, director of the SVLW (Swiss association for air and water hygiene), has this to say: “Most Cantonal building laws, or municipal building regulations, state the principle that a building must not endanger life or health of the building‘s users.” Furthermore, buildings must be erected according to the rules of the building trade, as laid down in the standards, directives and bulletins (SIA, SWKI).
Careful planning of ventilation systems
Today, however, an adequate supply of fresh air cannot be taken for granted. In densely built-up housing areas, normal ventilation through the windows is of limited value. A good room climate cannot be achieved by regular airing in all buildings – climate-regulating systems are a necessity. Building owners and ventilation planners should therefore conform to the specifications in the SWKI Directives – “Hygiene requirements for room air systems and devices” – starting with the positioning of the air intake, through the controls of the ventilation and heating systems to the instruction of the occupiers. In the case of more complex systems, the responsibilities for surveillance and maintenance must also be clearly defined. “The maintenance of the system should have high priority,” Alfred Freitag emphasises. To keep the ventilation systems functioning reliably, and to keep them hygienic, they must be carefully planned, constructed, regulated and maintained. Rotronic CO2 displays can then be used to monitor these ventilation systems, the data being read out via USB stick when necessary. Asked why Belimo decided in favour of the Rotronic CO2 displays, Alfred Freitag says, “We were very competently advised by Rotronic CEO Michael Taraba. He took care of our needs personally. In addition, the visualisation of the measured data was very important to us. They are simple and clear to read on the Rotronic display. Hitherto, Rotronic has proved a very reliable partner.” In addition, the Rotronic display permits global assessment of the air. It measures CO2 , humidity and temperature. This allows suitable countermeasures to be taken.
Product Snap Shot – CO2 Display
The wall-mounted or bench-top CO2 display is an inexpensive display unit that simultaneously measures and records CO2 , humidity and temperature. Equipped with the field-tested and proven ROTRONIC HYGROMER® IN-1 humidity sensor, this instrument offers unbeatable value for money. The instrument can be configured directly with buttons, and stored data can be exported to a USB stick for analysis with the free Rotronic software package SW21.
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