In this post we take a look at the important questions you should ask when looking for data loggers.
Since our founding over 50 years ago, data logging has always been a key requirement for our customers and as technology and regulations have evolved so have our products and solutions. We now offer a wide range of devices but it can get confusing knowing which approach to take.
When choosing a logging solution consider the following areas…
Parameters – What environmental conditions do you need to measure eg Humidity and Temperature
Accuracy/Calibration – How accurate do you need the results and do you require calibration.
Environmental Conditions – Both the logger operating conditions and monitoring conditions.
Access to Data & Reporting – Live data, manual download etc, software and reporting tools
Local Display – Live values, max/min and local alarming
Power Requirements – Mains, battery or PoE (power over ethernet)
Memory – How long can the device log and is data stable if power is lost
Cost – What it often boils down to, but always consider the cost of not changing what you are doing
Lets look in a bit more detail…
Parameters – Fairly self-explanatory but consider things like calculated parameters (dew point) , it might be better to use two separate devices rather than one. Rotronic offer Humidity, Temperature, CO2, Differential Pressure and Barometric pressure probes, but also many of our loggers accept analogue input signals so you can utilise existing or 3rd party instrumentation.
Accuracy & Calibration – Accuracy specifications can be mis-leading, if you care about your measurements we would always advice pre-delivery calibration. Also consider that often bulky loggers can be slower and more costly to calibrate vs devices with external probes. When considering humidity measurements drift is also a key factor.
Environmental Conditions – Consider both those you need to measure and where the logger will be placed. Many loggers have cable probes that can tolerate adverse conditions where the logger itself cannot. Also be wary of battery life, it is typically only stated for use at ambient conditions.
Access to Data / Reporting – Simple loggers typically require manual downloading of data. For large installations or where regular reporting is required this can quickly become a laborious task. Alternatively look for devices with a permanent connection to the monitoring software. Our latest RMS software provides live alarms, automated reports and users can access live data through a simple web browser, often saving time and money in the long run. Simple reporting is also key so that data can securely be shared. In compliant applications you may also require the ability for users to validate report authenticity.
Local Display – Useful for many applications but as data becomes always available can a mobile device act as the display for you data logger. For large spaces consider the ability to build dashboards in your software so that users can see data whilst operating.
Power Requirements – Devices with non user replaceable batteries lead to downtime and additional costs. Where possible mains or PoE connections ensure battery life is not an issue. Our latest wireless devices ensure >3 year battery life even when logging and transmitting data every minute.
Memory – Should be secure in the event of battery or power failure and sufficient to last either between download events or as a back up in case monitoring software / network connections fail.
Cost – Best to be realistic with your budgets, consider the time costs for not acting and down forget on going service costs such as validation and calibration.
As you can see from the simple overview above it is virtually impossible to have one logger for every application. At Rotronic we have a diverse range of solutions and even these do not cover all eventualities.
If you have monitoring requirements please do contact us to discuss further.
In short RMS provides a modern and complete monitoring system with a detailed web interface. The system provides users with ease of access to data, reliable and manageable alarms and extensive reporting. Importantly RMS can support existing hardware and interact with other software/hardware platforms.
RMS can be provided as a hosted cloud service or using a traditional licence whereby the client installs the system on their servers (local or cloud).
In summary RMS provides amongst other things…
Live interactive charts
Full reporting and automated/scheduled report generation
Complete event logging in line with GxP requirements
Full alarming with logic and time schedules
Email, phone, sms, relay and custom protocol alarm outputs
Auto back fill and retrospective alarms (ideal for transport logging)
Complete user rights management
Compliant to GxP designed around ease of validation
Core RMS hardware includes Ethernet, WiFi, industrial wireless and RS485 devices as well as full support for existing Rotronic devices, 3rd party analogue devices and 3rd party digital devices using any of the above interfaces. The below graphic outlines the wide range of options available.
Contact us for further information or visit our website
What is RMS – The Technical Answer…
Let’s now go a bit deeper. For many organisations once end-users approve of a system the challenge is getting the system approved and installed in line with wider corporate policies and security. So far we have found that in discussions with IT project managers and cyber security managers, RMS has met their requirements – usually much to the surprise of the end users who perhaps initially expect a protracted battle! Typically for larger more secure organisations software is required to be installed within their network rather than using the Rotronic Cloud service. Below we discuss the main elements of this type of RMS installation.
RMS has two core elements.
1. Webservice; This is software aspect of RMS. The webservice provides the interactive webpage to present data for end users and allow system configuration. The webservice also works in the background to interact with hardware and the database. Typically the webpage will be part of the local intranet with an address like rms.yourorganisation.com, optionally the webpage can also be made accessible from the internet outside your organisation (like our cloud service which is available at http://rms.rotronic.com/rms – request guest access to the demo system here). For the clients (end users) no special software or plugins are required just a standard web-browser.
More technically the RMS webservice is built around ASP.Net framework and runs under Windows IIS (internet information services). The webservice therefore requires a Windows Server (2008, 2012 or 2016). The RMS software can be run on a standard PC with IIS enabled but this is not usually advised except for specific applications.
A note on RMS hardware; All Rotronic hardware initiates communication with the webservice via port 80. For cloud applications this means only port 80 must be opened outbound to allow the devices to initiate outbound communications to the server. All gateways have standard IP configurations (DHCP or fixed).
2. SQL Database; The second part of the RMS is its database. All device, configuration, user and measured data is stored within a standard MS-SQL database. The database is accessed by the webservice to store and read data as required. An existing SQL server can be used if available otherwise SQL-Express is free to install.
More technically the RMS database requires Microsoft-SQL Express or higher, the database can be on the same server as the webservice or a separate machine.
As RMS is built around standard server based systems, there is full support for load balancing and failover, as such should a webserver or sql server fail a redundant/spare can take over. This is standard procedure for larger IT systems.
Some other technical points about RMS.
Supports LDAP (so you can use windows login and password)
No personal data stored outside SQL database (hardware only stores unique serial code, date, time and measured values – as such no private data passes between hardware and software).
Webpage data is binary coded and authentication uses AES128 encryption.
Key exchange uses diffie-hellman key alogrithm.
3rd party data / device support is possible via RESTful API or direct interaction with SQL database.
An overview of the RMS communication can be seen here.
For many projects clearly we go much deeper but hopefully this provides an overview. Our experience to date has shown that RMS is closely inline with what our clients expect in terms of operations and security. Further developments are always underway, lead by our customers and their requirements.
Please contact us if you wish to discuss a project or gather further information.
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
We are pleased to announce our latest training course schedule for 2016. Courses include in partnership with Dave Ayres from Benrhos Ltd our practical 3 day temperature, humidity and dew point calibration and measurement uncertainty courses. In addition, for those seeking greater depth we are running dedicated courses on measurement uncertainty and ISO 17025 run by Lawrie Cronin and Dave Ayres
8th – 10th March :: 12th – 14th July :: 15th – 17th November
– Three day course at Rotronic UK offices and UKAS laboratory
– Practical applied knowledge and best practice
– Max 8 attendees to ensuring tailored content
Ceramic drying is one of the most important processes in ceramic production technology. Quality defects of ceramic products are caused by improper drying. The drying affects the quality of the finished product, the throughput but also the overall energy consumption for ceramic manufacturing enterprises. According to various statistics, generally energy consumption during drying processes represents 15% of total industrial fuel consumption. However within the ceramic industry, the energy consumption used for drying accounts for a much higher percentage of the total fuel consumption. Therefore energy saving within the drying process is extremely important for all enterprises. Drying speed, reducing energy use , ensuring high quality products and reducing pollution are all basic requirements for any ceramic manufacturer today.
Measurement and Control in Ceramic Dying
Ceramic production is done through several main processes: casting, drying, glazing, firing…
The casting and drying are important processes for ceramic. A forming workshop is equipped with an intelligent control system. The control system regulates the relative humidity value using information provided via room and process sensors. Sensors have to measure accurately ad repeat ably despite the challenging and often dusty conditions. Humidification and dehumidification processes require substantial energy so tighter control is a huge energy saver for these industries.
A constant temperature is also achieved via the intelligent control system. With a stable temperature and stable relative humidity within the workshop, manufacturers ensure the quality of the ceramic body drying.
After stripping the body from the cast, the body contains a very high relative humidity level. During the drying process, the body may crack or deform due to the speed in which the product is dried (volume and shrinkage) which ruins the product and decreases the throughput.
Exactly this part of the process has become a major bottleneck within the production process of ceramic products.
In a casting workshop, stable environments can reduce the cracking and deformation effectively. It also improves the throughput rate of semi-finished products and shortens the drying period, also prolonging the life frame of the plaster cast.
So constant temperature and relative humidity according to the set values will help all factories to improve the throughput, reach an optimal drying speed and deliver the best quality results available.
How can we help?
Rotronic provides a range of instruments for environmental monitoring and control.
Rotronic HC2-IC industrial temperature and humidity probes, are successfully working in these tough applications, the probes are installed on the roofs of drying chambers and resist chemical pollution. With a flexible HF5 transmitter, the outputs can be set to the customers requirements.
With both digital and a range of analogue outputs available as well as several probe mounting options, products can be selected for all applications.
Measurement data can be viewed on HF5 with display or remotely via HW4 software. Ease of calibration and sensor replacement ensures down time is kept to an absolute minimum.
Its been pretty windy recently, So wind farms are probably doing quite well at the moment. The biggest wind farm in the world, at the moment, is the London array, which can produce 630MW of power.
Wind Energy in General
The future is very encouraging for wind power. The technology is growing exponentially due to the current power crisis and the ongoing discussions about nuclear power plants. Wind turbines are becoming more efficient and are able to produce increased electricity capacity given the same factors.
Facts & figures:
There is over 200 GW (Giga Watts) of installed wind energy capacity in the world.
The Global Wind Energy Council (GWEC) has forecasted a global capacity of 2,300 GW by 2030. This will cover up to 22% of the global power consumption.
Converting wind power into electrical power:
A wind turbine converts the kinetic energy of wind into rotational mechanical energy. This energy is directly converted, by a generator, into electrical energy. Large wind turbines typically have a generator installed on top of the tower. Commonly, there is also a gear box to adapt the speed. Various sensors for wind speed, humidity and temperature measurement are placed inside and outside to monitor the climate. A controller unit analyses the data and adjusts the yaw and pitch drives to the correct positions.
The formula for wind power density:
W = d x A^2 x V^3 x C
d: defines the density of the air. Typically it’s 1.225 Kg/m3. This is a value which can vary depending on air pressure, temperature and humidity.
A^2: defines the diameter of the turbine blades. This value is quite effective with its squared relationship. The larger a wind turbine is the more energy can be harnessed.
V^3: defines the velocity of the wind. The wind speed is the most effective value with its cubed relationship. In reality, the wind is never the same speed and a wind turbine is only efficient at certain wind speeds. Usually 10 mph (16 km/h) or greater is most effective. At high wind speed the wind turbine can break. The efficiency is therefore held to a constant of around 10 mph.
C: defines the constant which is normally 0.5 for metric values. This is actually a combination of two or more constants depending on the specific variables and the system of units that is used.
Why the need to measure the local climate?
To forecast the power of the wind over a few hours or days is not an easy task.
Wind farms can extend over miles of land or offshore areas where the climate and the wind speed can vary substantially,
especially in hilly areas. Positioning towers only slightly to the left or right can make a significant difference because the wind velocity can be increased due to the topography. Therefore, wind mapping has to be performed in order to determine if a location is correct for the wind farm. Such wind maps are usually done with Doppler radars which are equipped with stationary temperature and humidity sensors. These sensors improve the overall accuracy.
Once wind mapping has been carried out over different seasons, wind turbine positions can be determined. Each turbine will be equipped with sensors for wind direction, speed, temperature and humidity. All of these parameters, the turbine characteristics plus the weather forecast, can be used to make a prediction of the power of the turbine using complex mathematics.
There is a small weather station on the top of this wind turbine
The final power value will be calculated in “watts” which will be supplied into power grids. Electricity for many houses or factories can be powered by this green energy.
Why the need to measure inside a wind turbine?
Wind farms are normally installed in areas with harsh environments where strong winds are common. Salty air, high humidity and condensation are daily issues for wind turbines.
Normal ventilation is not sufficient to ensure continuous operation. The inside climate has to be monitored and dehumidified by desiccant to protect the electrical components against short circuits and the machinery against corrosion.
Internal measurements are required to ensure continuous operation and reduce maintenance costs of a wind farm.
I recently visited a facility where they were doing a lot of research into plant biology. As such, it was important for them to have their seeds stored at exactly the correct temperature and humidity to prevent germination or degradation of the seeds.
Seed storage in general
Around 10000 years ago when the first human beings stopped hunting and gathering wild plants, and started to cultivate on farms, preserving and storing seeds became important.
There are various reasons to store seeds, for example, simply preserving grain for consumption later in the year or for sowing during the following season. A little more complex is the collection and preservation of seeds for a longer period of time. This may be done to protect species from extinction or to ensure genetic variety for future generations. Long term storage is also necessary as a back up in case of catastrophic events, such as natural disasters, and disease outbreaks. This type of long term storage is usually done in well protected storage building called seed banks.
A range of seeds in storage
Inside each seed is a living plant embryo which, even in a state of dormancy, breathes through the exchange of gases across its membrane, and is constantly undergoing metabolic processes, also known as aging. The natural lifespan of a seed is influenced by several factors including: permeability of the seed coat, dormancy, and seed physiology. But one of the most important factors is the external environment the seed is exposed to. Temperature and humidity play a key role in the storage capabilities of seeds.
Facts & figures:
The oldest seed that has grown into a viable plant was a Judean date palm seed about 2,000 years old.
The Millennium Seed Bank Project in the UK is the biggest seed bank in the world. Currently they store 31880 species and 1`907`136`030 seeds.
China, with 197 million metric tons, is the world`s biggest producer of rice.
Why the need to measure humidity?
Controlling the environment in seed storage is essential for maintaining the germination capacity of seeds, or simply the quality of the seed as a food.
Every 1% decrease in the moister content will double the storage life. The same applies for every 5°C decrease of the storage temperature.
A rule of thumb: the sum of the temperature in degrees F and the % relative humidity should be less then 100 for good seed storage conditions.
Proper storage conditions maintain relative humidity levels
between 20% and 40%, giving corresponding seed moisture contents between 5% – 8%, depending on the type of seed. This range is safe for most seeds. When seed moisture content drops too low (<5%), storage life and seed vigor may decline. When seed moisture content goes above 8%, aging or seed deterioration can increase. Deterioration effects the integrity of the cell membrane, along with several biochemical processes, which overall results in loss of vigor and viability. Seed moisture contents above 12% will promote growth of fungi and insects. Most seeds cannot germinate until seed moisture contents go above 25%.
A newly germinated seed
Seed preparation for long term storage (Seed bank)
To prepare for long term storage, seeds are first put in to a drying room where temperature and humidity is carefully kept at 15°C and 15% relative humidity. Under these conditions the seeds gradually dry out. They are then cleaned, counted and put into airtight containers, before being placed in a seed bank at -20°C. The seeds are then tested for viability on a regular basis.
Companies across many industries needing to perform regular monitoring and calibration have never faced a more challenging environment. Stricter compliance requirements mean companies are under greater pressure to deliver accurate and reliable data, whilst internal budget restrictions demand the most cost effective and efficient solutions.
Can modern measurement & calibration techniques help your business operations?
It is well known that accurate measurements reduce energy use and improve product consistency. Instrument users, calibration laboratories and manufacturers are constantly looking for smarter ways of operating and are responding with innovations that are transforming the measurement and calibration industry.
New ways of working
Industrial environments are now more automated and interconnected than ever before and companies need to ensure that their infrastructure and processes have the ability to respond and adapt to industry changes. With the introduction of newer, more complex instrumentation, organisations can often be slow to recognise the additional business benefits that can be achieved by replacing a traditional method that (offers a short term result) with a more modern method (that delivers a longer term sustainable solution). Implementing a new approach can also help re-position the calibration process from being viewed simply as a cost to business to one that helps deliver improved process and energy efficiencies with a return on investment.
Historically, in-situ calibration has been the standard approach; however, advances in technology means that there is now a viable alternative whilst still maintaining the growing demand for on-site services. With the market moving away from analogue to digital signal processing, interchangeable digital sensors are proving to be a more practical solution for both large and small organisations alike. As businesses look for greater automation and productivity, modern interchangeable digital sensors are allowing calibration to be achieved much more quickly without the costly implications of operational downtime and on-site maintenance.
Why calibrate? – The only way to confirm performance In unsettled economic times it can be tempting to simply extend the intervals between calibration cycles or to forgo calibration altogether. However, neglecting system maintenance and calibration will result in reduced performance and a loss of measurement confidence, ultimately leading to a failure to meet compliance standards. Measurement drift over time negatively impacts on processes and quality. Regular, accredited calibration demonstrates compliance, but equally importantly, sends a message to customers that quality is taken seriously and that they can be confident in both the process and the final product.
Traditional In-Situ Sensor Calibration
Until recently most humidity calibrations were performed on-site in-situ. Larger organisations with multiple instruments generally found it more convenient to have their own in-house calibration instruments with dedicated technicians working on-site. Smaller organisations unwilling or unable to invest in on-site calibration equipment had the option to engage the services of a commercial calibration provider.
In most cases, trained instrument technicians are required for in-situ calibration work; the equipment is brought to the probes and generally only one probe can be calibrated at a time. One of the main disadvantages of this process is the impact that it has on production downtime, as typically a salt or chamber based calibration can take more than three hours. Moreover, as the processes or control systems are interrupted during calibration, the actual conditions can be unknown.
Modern Ex-Situ Sensor Calibration
Companies keen to avoid the impacts of in-situ calibration and/or operational downtime caused by the replacement of failed hard wired instruments are opting instead for the flexibility and convenience of interchangeable sensors and modern portable calibration generators. Instead of bringing in equipment to calibrate in-situ, the technician brings pre-calibrated probes directly from the laboratory (on-site or external). Using interchangeable digital sensors, the pre-calibrated probes can be exchanged with the in-situ probes in seconds (known as hot swaps), saving time and avoiding operational disruption. If a wider system loop calibration is required, digital simulators are applied and provide any fixed values exactly and instantly. The old probes are then taken back to a calibration laboratory and calibrated accordingly. This adds the benefit that an external accredited laboratory can be used without issue.
Improved accuracy and traceability?
By ensuring that all calibrations are performed within dedicated laboratories as opposed to ad-hoc locations, better procedures and instrumentation can be utilised. In addition, time pressures are usually reduced as processes and monitoring systems are unaffected during calibration. As such calibrations are typically performed to a higher standard leading to lower associated measurement uncertainty (every calibration will have an uncertainty associated with it – whether it is defined or not). Overall in most circumstances these methods deliver greater reliability, improved traceability and importantly, reduces on-site workload and limits operational downtime.
CASE STUDY – Meeting the demands at the National Physical Laboratory, London.
When the National Physical Laboratory (NPL) in London needed to replace their entire building management system (BMS), they turned to Rotronic Instruments (UK) for an integrated solution to the sensors and calibration. The NPL was looking for both a complete range of temperature and humidity sensors and instrumentation, and the fulfilment of the calibration and commissioning needs of these instruments. Working closely with the project stakeholders, the Rotronic Instruments (UK) team developed a tailored solution, matching the instruments and service to the project requirements.
The decision by the NPL to replace the BMS was brought about by the need for tighter control, greater reliability and easier calibration. One of the key elements in achieving these objectives was the use of interchangeable probes. This immediately limited time-consuming and disruptive on-site sensor calibration to a minimum. Every probe’s digital output was calibrated in Rotronic Instruments’ (UK) UKAS accredited laboratory, and each transmitter’s analogue output was calibrated using a simulated digital input. To resolve any measurement errors in-situ between the calibrated sensors and uncalibrated BMS, each installed high accuracy instrument was loop calibrated and adjusted. Typical installations errors corrected for to date on the brand new BMS are ±0.5 %rh and ±0.25°C; a significant result for labs requiring tolerances of better than 1 %rh and 0.1°C.
Whilst the use of high performance instruments was essential, not every sensor location or application could justify this approach. However, mindful of the NPL’s long term objectives, even the lowest specification thermistor products were customised to provide long-term performance and low drift. Additionally, a robust commissioning procedure and training for key personnel was developed to enable ongoing commitment to delivering quality measurements. Finally, it was effective communication and regular on-site interaction with all the stakeholders that helped deliver a successful outcome to this substantial project.
All companies that need to perform regular monitoring and instrument calibration should be constantly reviewing their processes and questioning whether their operations and procedures are delivering the maximum return for their business. As increased regulatory compliance and demands for improved energy efficiencies continue to grow, traditional processes may no longer offer the optimum solution. An organisational mindset change may be needed to move calibration from being seen as a fixed cost to a process that can help deliver business objectives through ongoing cost and energy efficiencies.
With the advent of calibration methods that can significantly reduce in-situ disruption, downtime is minimised, labour costs are reduced and productivity improved. Using interchangeable digital systems increases the accuracy and traceability of calibrations, resulting in higher quality product.
Choosing the right calibration methodology may require new thinking and a different approach, but those companies that get it right will end up with a modern, flexible system that both achieves compliance and delivers long term cost and energy efficiencies to their business.
For more information on the NPL case study or how your business can develop innovative and efficient monitoring solutions please contact us.
We tend to spend most of our time looking out to the industry and marketplace for the future trends and next opportunities. However, last week the staff at Rotronic UK spent some useful time reflecting on our recent history, current methods of working and how to develop ourselves for the future – whatever it maybe.
In the sessions, led by our in house project and change manager we were encouraged to explore our ideal future both personally and for the UK arm of Rotronic. Sessions were run for our service and calibration teams and separately for sales and admin teams. The sessions provided a useful opportunity to learn from each other and better understand the internal processes we all take for granted. As well as providing time to explore what the key issues are ad what we would like to see in the future.
Some clear areas were identified for the future but not so broad that we will be unable to tackle them and report back on progress in the coming weeks and months. Our change guru is now digesting the sessions and we will begin a 3 – 6 month period of putting into practice and reflecting on the new goals and actions we have collectively embraced.
As a small team in the UK working in within a complex field and highly diverse marketplaces it is important to maximise the internal knowledge and skills we have. In addition, we are all focused towards precision measurement and quality service; things that cannot be achieved without a consistent effort and shared values.
There is always room for improvement but hopefully we are remaining open-minded and have a positive drive for the future.
Some of the new ventures and changes will be important for our customers and partners… we will keep you posted!!
Dr. Jeremy Wingate Rotronic UK
News, views and interesting things from the world of metrology