Great to see everyone at the 2014 ISM in Grindelwald!
Control of Temperature and Humidity in Hospitals
Temperature and relative humidity affects the airborne survival of viruses, bacteria and fungi. Thus environmental control in hospitals is important because of infectious disease transmission from the aerosol or airborne infection.
Environmental exposure is a common hazard for all such organisms (whether viruses, bacteria or fungi) during this journey between hosts. Factors such as temperature, humidity (both relative and absolute), sunlight (ultraviolet light) exposure and even atmospheric pollutants can all act to inactivate free-floating, airborne infectious organisms.
Maintaining hospital premises at a certain temperature and a certain relative humidity (%rh), likely to reduce the airborne survival and therefore transmission of influenza virus. Temperature and RH settings in different parts of a hospital differ slightly between summer and winter. In summer, the recommended room temperatures range from 23°C-27°C in the ER (emergency room), including in-patient and out-patient areas, as well as X-ray and treatment rooms and offices. The corresponding recommended RH is fairly constant throughout the hospital, between 50- 60%rh. In winter, the recommended temperatures are generally slightly lower, ranging from 20°C in some in-patient and out-patient areas, as well as offices, up to 24°C -26°C in in-patient and out-patient areas.
The recommendations for the newborn baby and the hydrotherapy treatment rooms are higher at 27°C –28°C. Again, the corresponding recommended range of RH is fairly constant, but slightly lower than for summer, ranging from 40%rh -50%rh, but up to 55%rh–60%rh for more critical areas, such as operating theatres and recovery, the intensive care unit and childbirth/delivery suites.
Temperature is one of the most important factors affecting virus survival, as it can affect the state of viral proteins and the virus genome. Virus survival decreases progressively at 20.5°C –24°C then < 30°C temperatures. This relationship with temperature held throughout humidity range of 23%rh- 81%rh.
Facts & figures:RH (expressed in percentage) describes the amount of water vapor held in the air at a specific temperature at any time, relative to the maximum amount of water vapor that air at that temperature could possibly hold.
At higher temperatures, air can hold more water vapor, and the relationship is roughly exponential—air at high temperatures can hold much more water vapor than air at lower temperatures.
Why do we need to measure relative humidity?
Virus: The survival of viruses and other infectious agents depends partially on levels of RH. At a temperature of 21°C, influenza survival is lowest at a mid-range 40%rh–60%rh. It is also important to note that temperature and RH will always interact to affect the survival of airborne viruses in aerosols.
At High temperatures < 30°C and at high RH < 50%rh may reduce the survival of airborne influenza virus.
Bacteria : For bacteria, the effect of carbon monoxide (CO), enhanced the death rate at less than 25%rh, but protects the bacteria at higher RH ~ 90%rh.
Temperatures above about 24°C appear to universally decrease airborne bacterial survival.
Fungi: Ventilation systems controlling Temperature and Humidity have a significant effect on indoor levels of airborne fungi, with air-handling units reducing, but natural ventilation and fan-coil units increasing the indoor concentrations of airborne fungi.
Dehumidification as well as HEPA filtration can be used to improve indoor air quality.
Different airborne infectious agents (i.e. viruses, bacteria and fungi) will have differing conditions under which they may be optimally suppressed; it will need to be decided which airborne pathogen poses the most risk to patients and staff alike in hospitals.
Thus, in reducing infectious disease transmission specific environmental control of temperature and humidity is vital for hospitals and healthcare premises.
Rotronic can offering a complete system for hospital measurement applications: a proven system that enables healthcare facilities to control and monitor their conditions and remain in conformance with internal or regulatory guidelines.
With the combination of both analogue outputs, controlling the air-conditioning, and digital outputs, linked up to the Rotronic HW4 monitoring software, end users have a clear overview of conditions.Dr. Jeremy Wingate
Beer brewing in general
There is no exact date, as to when the first beer was brewed but already at the beginning of the fifth millennium BC, people in southern Mesopotamia, in a region known as Sumer (modern Iraq), were brewing beer.
Beer, like other commodities such as wheat and other grains, was used as a currency. A clay tablet, dating from 6’000 BC contains one of the oldest known beer recipes.
The basic ingredients of beer are: water; a starch source: which is able to be fermented; yeast: to produce the fermentation; a flavouring such as hops. Yeast is the microorganism that is responsible for fermentation. Specifically Saccharomyces cerevisiae is the species of yeast that is used for brewing.Facts & figures:
Beer is the third most popular beverage in the world, coming in directly behind tea and water.
American beer is made mostly from rice. This was invented to give American beer a lighter taste and tap into the market of women buyers.
In the UK 28 million pints of beer are consumed every day, which equates to 100 litres per head each year.
Belgium has over 400 different beer brands.
Cenosillicaphobia is the fear of an empty glass.
There are several steps in the brewing process, which include malting, milling, mashing, lautering, boiling, whirl-pooling, fermenting, conditioning, and filtering.
Step by step brewing:
- Malting: germination of cereal grains. The sprouted cereal is then kiln dried at around 55°C. Milling: grinding of the malted cereal.
- Mashing: the cereals are mixed with water and then heated.
- Lautering: separation of the mash: the liquid (wort) is separated
from the residual grains.
- Boiling: the wort is boiled to ensure sterility and then hops are added for flavour!
- Whirl-pooling: the wort is sent into a whirlpool, removing the dense particles using centrifugal force.
- Fermenting: yeast is added to the wort: conversion of the carbohydrates to alcohols and carbon dioxide – the chemical conversion of sugars into ethanol!
- Conditioning: the tank is cooled and the yeast and proteins separate from the beer. This conditioning period is also a maturing period.
- Filtering: the beer is filtered: stabilising the flavour.
- Packaging: the beer is packed then to the customers
Why the need to measure the carbon dioxide?
Carbon dioxide Carbon dioxide (CO2) is a naturally occurring chemical compound. It is a gas at standard temperature and pressure.
We inhale oxygen and exhale carbon dioxide. The carbon dioxide level in exhaled air is rather constant: around 3,8%. When carbon dioxide is exhaled it will quickly be mixed with the surrounding air even indoors and provided that the ventilation is good, the concentration will be reduced to harmless levels. Indoor carbon dioxide levels usually vary between 400 and 1’200 ppm (parts per million). Outdoor carbon dioxide levels are usually 350 – 450 ppm.
Beer brewing process: Heavily industrialised or contaminated areas may periodically have a higher concentration of CO2. Carbon dioxide is released during the beer brewing process and as you will see below, CO2 is toxic for living organisms. In brewery environments where process generated carbon dioxide is widely present, the maximum permitted carbon dioxide concentration according to most standards is as high as 5’000 ppm (5%) during an 8 hour working period.
Beer storage: Most beer leaves the brewery carbonated: beer and carbon dioxide are sealed in a container under pressure. It can be carbonated during fermentation but it can also be carbonated in the bottle. In this case the beer is allowed to ferment completely. It is left unfiltered which leaves active yeast suspended in it. A small amount of sugar is then added at bottling time. The yeast begins to act on the sugar: CO2 is released and absorbed by the beer.
Beer can also be force carbonated, in which case it is allowed to fully ferment. Then CO2 is pumped into a sealed container with the beer and absorbed by the liquid. In this case, a tank of carbon dioxide will also be required. Undetected leaks in a gas system is a costly waste and a safety risk to personnel. While small leaks are inherent in any gas system, those of significant size raise the level of economic and safety risk.
How does CO2 affect the human body?
Due to the health risks associated with carbon dioxide exposure, there are regulations and laws in place to avoid exposure! The US National Institute for Occupational Safety and Health (NIOSH) states that carbon dioxide concentrations exceeding 4% are immediately dangerous to life and health.
In indoor spaces occupied by people: concentrations higher than 1’000 ppm will cause discomfort in more than 20% of occupants. At 2’000 ppm, the majority of occupants will feel a significant degree of discomfort and many will develop nausea and headaches.
Case study: The lake Nyos
The lake Nyos is a crater lake situated in Cameroon. In 1986, a pocket of magma from under the lake, leaked a large amount of CO2 into the air. The result was suffocation of around 1’700 people and 3’500 livestock!
As we take beer brewing seriously we will be sure to test a number of varieties with our colleagues from the world over at the Rotronic 2014 International Sales meeting in Grindelwald next week!Dr Jeremy Wingate
The Rotronic HygroGen2 (HG2-S) is known globally an amazing piece of instrumentation. The fastest relative humidity and temperature generator to set point on the market and loved in the pharmaceutical world. The HG2-S has many advantages compared to other chambers and new developments are making the unit even better. With AutoCal+ (direct communication with an MBW/RHS 473 Chilled Mirrors) and Remote Control (HG2-S control any web enabled device) more and more possibilities are available.
Our HQ Rotronic AG has invested into After Sales and today, like Rotronic Germany are offering more and more on-site calibration. With the HG2-S, it is possible to offer a fast and efficient calibration with direct delivery of calibration certificates and direct repairs on-site when necessary
A short story is available on our Swiss HQs Blog (only in German). As seen in the photo, in order to deliver a very quick turnaround (30 probes, within 4 hours) three HG2-S units were used at fixed temperatures and relative humidity levels. Return of investment is quickly achieved with the HygroGen through the ability to provide fast, high quality calibrations. If you are interested in setting up your own on-site calibration service, let us know, we will be happy to help!
With the new AutoCal+ function and the MBW 473, you can reduce the uncertainties of your setup and with the remote function, you can multitask and work more efficiently.
All information for the HygroGen2 Humidity and Temperature Generator is available on the Rotronic website.
If you have any questions about the HygroGen2 please do not hesitate to contact us!Dr Jeremy Wingate
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.
Rotronic have prepared a new White Paper on the subject of how modern digital probes and instrumentation are enabling new methods of field calibration. Download below…
No extraneous sounds, vibrations or electromagnetic fields find their way into the noise-free lab at the Binnig and Rohrer Nanotechnology Center in Rüschlikon. Moreover, a temperature sensor ensures that experiments on new switching elements for computer chips are not affected by temperature fluctuations.
Today, a single computer chip contains over a billion transistors, a far cry from the ten transistors in the first integrated circuit in 1958. In the intervening years, the structures have become so small that individual layers are just a few atoms thick. This has created a new problem of electrons flowing between layers. In order to prevent this from happening, researchers are endeavoring to reinvent the transistor and to explore new types of components.
The solution lies in silence
Switzerland is home to a world-renowned laboratory in which scientists are working on the transistors of the future: the IBM research laboratory in Rüschlikon. The location’s easy accessibility is not exclusively advantageous: when a truck passes by, it causes the samples to shake under the electron microscope. In 2011, the Binnig and Rohrer Nanotechnology Center opened six integrated laboratories with exceptionally high protection against external factors: the noise-free labs. They are built directly on rock, the actual measurement set-ups mounted in turn on concrete blocks that float on a cushion of air. Forty-ton trucks can now race by without vibrating the sample. Another problem is noise. To keep it out, the labs are equipped with thick doors. Even the scientists present were too loud and were obliged to control the experiments from a separate room.
Precise room temperature
A temperature difference of just a few degrees would be capable of moving a sample by several 100 nanometres per hour with disastrous consequences for structures in the range of 1 – 50 nanometres. A sensor is therefore used to measure the temperature and air humidity. IBM is using a Rotronic transmitter capable of measuring temperature to 0.1 °C with absolute accuracy for this purpose. This corresponds to the maximum temperature drift permitted in the laboratory over a 1-hour period. At the same time, the sensor measures the relative humidity of the air which is required to remain within 35 and 55 %RH and not fluctuate by more than 5 %RH. The sensor is even capable of measuring the air humidity to exactly 0.8%RH thanks to an integrated chip.
Researcher Heike Riel makes good use of the quantum effects to develop small transistors that are also highly energy efficient. Instead of an operating voltage of somewhat over 1 V commonly employed today, they would work with voltages of less than 0.5 V. Rolf Allenspach aims to utilized electron spin: spin-up corresponds to a logical 1, spin-down to a logical 0. The chief attraction of this is that much less energy is required to change the spin than to displace the electron as is the case in transistors today.
As we continue to measure relative humidity in more and more environments with ever increasing accuracy demands, we are pushing the humble capacitive humidity sensor into new realms.
Accuracy, drift, operating range and chemical resistance are key challenges for the relative humidity sensor industry. Our sensor experts work hard to develop new polymers and construction methods to ensure the best performance. At the same time advanced electronics and probe housings enable digital calibration and complex temperature corrections to further increase accuracy and performance. A final and often neglected part of ensuring a relative humidity probes performance is its filter. The correct filter ensures fast response and environmental protection. Filters also offer mechanical protection and eliminate damage caused by extreme airflow.
However understanding why sensors fail is often difficult to predict or understand. In many cases the chemicals and contaminants that sensors are exposed to are unknown. In these situations often selecting the best sensor can only be achieved through mutual relationships built around quality support and service.
In the UK we have worked closely with many customers and in combination with our Swiss technical divisions to select and develop solutions for some highly aggressive and challenging environments. Some of these projects are examined below in more detail.
Hydrogen peroxide vapour sterilisation.
– Hydrogen peroxide vapour is used to chemically sterilise environments and products by generating a vapour of toxic Hydrogen Peroxide. When the humidity reaches the dew point of the surfaces condensation forms sterilising all surfaces. However the chemicals are also highly aggressive to humidity sensors and constant cycles of saturation worsen the effects.
– Making use of Rotronic’s specifically designed H2O2 resistant sensor as well as additional conformal coating to protect exposed connections in further combination with improved customer understanding around handling and storage, has resulted in a solution that has exceeded customer expectations. Importantly, whilst this was not achieved first time around, through a partnership driven towards the end goal we achieved success.Chemical degradation on the sensor surface Commercial composting.
– Accelerated commercial composting is an impressive sight to see. The chemical and biological processes occurring are complex and surprisingly aggressive. The wrong materials can literally become part of the final compost if you are not careful. Chemically resistant sensors help to provide some longevity to instruments but one of the key areas requiring extra attention is around cable and filter design. Modifying a standard industrial grade sensor with bio-resilient cables ensures the probes are not eaten alive!
Highly accelerated life testing.
– As a supplier to many chamber manufacturers and companies providing testing services this is a common application. Chambers are cycled between high and low temperatures and humidities to simulate many years aging over a short period of time. The same effects are happening to the humidity sensor – critical for the control or validation of the chamber conditions. Using industrial sensors with electronics isolated away from chamber space reduces the effects of the sudden changes. But also care taken placing the sensor away from humidity outlets and well into the chamber to avoid stem conduction all help to avoid the sensor becoming saturated as temperature cycle – which is one of the main causes for corrosion and drift. Finally, careful filter maintenance is always important.
Swimming pool monitoring and control.
– Our featured image shows chemical formation on a non-Rotronic sensors connections. Rotronic uses inert metals in the sensor design to reduce the re-activity of the sensor to chemicals in the environments. Swimming pools have a mix of high humidity, chemicals and high temperatures which work together to corrode unprotected electronics. Sensor location is key to avoid direct exposure to spray and neat chemicals. Suitable filters and if required chemical resistant sensors have proven highly successful where other instruments have failed.
So you can see not all applications are easy and we have not even begun to explore the basic issues of accurate measurement and control present with every humidity sensor installation. However our belief and aim is that through communication and partnerships we can provide the right product to ensure the desired mix of performance, resilience and price for our customers – it’s not easy but it makes life interesting!
Dr. Jeremy Wingate