Gas sensing

Delivering products for life and safety protection wherever needed

Ensuring that products reach customers on time is a critical part of any business, but more so for those who deal in products designed to help keep workplaces and staff safe. ION Science, as global leaders in the development, manufacturing, and distribution of gas detection instruments, are all too aware of the need to get product to customers on time. Their team have dedicated significant time and resource to creating a network of reliable distributors around the globe, supported by knowledgeable technical staff.

The importance of having secure, reliable supply chains was truly highlighted to the world this year. Incidents such as the COVID-19 vaccine shortages and supply issues and the Suez Canal blockage with the Ever Given both showed how easily critical supply lines can be disrupted, and how important it is to always have solutions that mean you can meet customer demand no matter what.

ION Science, as a leading OEM for gas detection equipment, understands these challenges and works closely with its global network of distributors and technical offices. This allows for products to be shipped and on-site within exceptional delivery times. ION Science’s industry leading instruments such as the Tiger are available for delivery within days, not weeks, at all of their major global locations, and stock levels are maintained so there is never any unnecessary delay.

In Europe, ION Science’s German office boasts some of the most impressive lead times for the core PID product portfolio. The Tiger range has a guaranteed delivery of 24 hours, with Falco and Cub products generally within 3 working days. Customers can rely on ION Science to get products exactly where they need to be in a fast timeframe. Not only that, but their network of expert technical staff is also available to help customers who need help with specific VOC detection ranges or technical applications.

Elsewhere, ION Science Italy also offers 24-hour turnaround of Tiger product orders, and in France, the full range of PID products is available with a 1-2 day lead time. For India, one of ION Science’s key centres for customers, Tiger can be available for delivery within 24 hours, with Falco generally delivered in 5 working days.

This is just a snapshot of ION Science’s exceptional commitment to lead times and ensuring that products are with customers as quickly as possible. A crucial part of maintaining such efficient lead times is effective stock management, something which ION Science manages closely with all offices and distributors, so no level ever falls too low.

By working with a trusted global network of suppliers, distributors and technical staff, ION Science demonstrates its expertise as a leading gas detection manufacturer goes beyond technical knowledge. Their commitment to reliability and delivery no matter what challenges customers may face means more staff and workplaces can be kept safe from dangerous levels of exposure and keep businesses running smoothly.

Pioneer in solid state gas sensors launches new website

Gas Sensing Solutions, a pioneer in solid state gas sensor technology is delighted to announce the launch of its new website www.gassensing.co.uk. The website places a strong focus on the user experience and includes an easy-to-use parametric search function making it easy for engineers to select the right GSS sensor.

The website has been given a complete overhaul with an emphasis on making it easy to access all the important sensor information in one place. Customers are presented with a product landing page, showcasing each sensor and its key attributes. The product landing page also gives customers the option to filter the sensor choice based on their own parametric requirements including measurement range, sample method and operating temperature range.

Each individual sensor landing page brings together a complete set of technical data. All sensor documentation and other user information including data sheets, application notes, evaluation board user guides, software and other helpful information have been brought together in one place.

When asked about the new website, Julian Hayes, CEO of Gas Sensing Solutions said “In a time when events and customer visits have been put on hold, it is fundamental that our website is able to facilitate our customers in their search for information on our sensors. Our site structure has been streamlined to help customers to find what they need, and the content revamped to ensure our customers understand what our sensors can do in real-world applications.”

 

Formaldehyde sensing made easy

Sensirion has launched its new formaldehyde sensor module, the SFA30. The SFA30’s innovative electrochemical cell design, dedicated electronics including an onboard Sensirion humidity and temperature sensor, and advanced algorithms, enables highly reliable and selective formaldehyde detection at very low concentrations. This new sensor thus targets the appliance market focusing on indoor air purification and ventilation systems as well as indoor air quality monitors.

Formaldehyde is typically released slowly and continuously from furniture, building materials, paint and coatings. It is a harmful and carcinogenic gas that causes conditions such as “sick building syndrome”. Caused by inadequate ventilation and chemical contaminants from indoor sources, “sick building syndrome” can lead to various symptoms for building occupants such as acute discomfort, headache, eye, nose, or throat irritation, dizziness and nausea, difficulty in concentrating, fatigue, and sensitivity to odours. Formaldehyde is a background gas known to be relevant in very low concentrations. The World Health Organization (WHO) for example establishes an indoor air quality guideline for exposure to formaldehyde of only 80 ppb as a 30-minute average.

Adding to Sensirion’s environmental sensor portfolio, the new SFA30 formaldehyde sensor module is based on an amperometric electrochemical working principle. It provides unrivalled formaldehyde sensing performance enabled by an ultra-low cross-sensitivity to other VOCs. Relying on Sensirion’s experience in environmental sensing and a patented electrochemical cell with anti-dry technology, the SFA30 offers excellent long-term stability and an outstanding six-year service lifetime. The on-board humidity and temperature sensor provides accurate readings and enables a fully temperature and humidity-compensated and factory-calibrated formaldehyde concentration output in ppb (parts-per-billion). With selectable digital UART and I2C interface options, a standard electrical connector, and versatile mounting options it offers customers the perfect solution for easily integrating a highly reliable sensor into their application.

“By having improved performance, long-term stability and reliability with our new formaldehyde sensor module, we were able to tackle an issue in existing technologies, making formaldehyde sensing easy and truly trustworthy,” says Niculin Saratz, Director Product Management Gas Sensors at Sensirion.

The new SFA30 sensor module is now available worldwide through Sensirion’s distribution network. Additionally, Sensirion offers the SEK-SFA30 evaluation kit for fast and easy prototyping. The SEK-SFA30 comes with a UART-USB cable for a plug-and-play connection to a PC and evaluation with Sensirion’s easy-to-use SEK-ControlCenter viewer software. For connecting the sensor to prototyping platforms such as Arduino or RaspberryPi, a 7-pin jumper wire cable is provided.

Sensirion strengthens its portfolio by acquiring micro gas-analyser specialist Qmicro

Sensirion has completed the acquisition of Qmicro, an innovative OEM supplier of miniaturised gas-analysis technologies. Qmicro, based in Enschede, The Netherlands, develops, manufactures, and supplies micro gas analysers based on microelectromechanical (MEMS) gas chromatography (GC) technology. Qmicro’s most important application areas include industrial process control as well as natural and biogas characterisation.

With this acquisition, Sensirion expands its gas sensing portfolio from components and modules to stand-alone micro gas analysers for industrial applications. Many industrial applications require high selectivity and accuracy of gas composition measurements. Micro gas-chromatography technology allows to very selectively and accurately determine the constituents of gas mixtures, enabling Sensirion to expand its gas-sensing offering for its customers from components and modules aimed at high-volume applications to micro gas analysers addressing high-end applications.

Qmicro was founded in 2013, has sixteen employees, and offers very compact, easy-to-use micro gas analysers based on its MEMS-GC technology. Combined with Sensirion’s expertise in MEMS, industrialisation, and the development of highly cost-effective sensor solutions even further miniaturisation and integration becomes possible, benefiting both Qmicro’s and Sensirion’s customers.

Mark Kok, Managing Director and Co-Founder of Qmicro

Core applications of Qmicro’s analysers include the determination of the calorific value of natural gas in distribution networks, monitoring the composition of gas mixtures used in industrial processes, and in the future environmental monitoring. Qmicro’s and Sensirion’s end markets partially overlap and partially complement each other. The acquisition allows Sensirion to leverage its global marketing and sales network.

Mark Kok, Managing Director and Co-Founder of Qmicro comments: “We are excited to join forces with Sensirion, which will enable us to more efficiently scale-up our processes and accelerate growth.”

Marc von Waldkirch, CEO of Sensirion

“Sensirion very cordially welcomes all Qmicro employees and looks forward to further developing the Enschede location as a competence centre for micro gas analysers,” says Marc von Waldkirch, CEO of Sensirion.

Biogas and anaerobic digestion in relation to CH4 methane monitoring

The use of biogas as a renewable energy source currently accounts for 10 per cent of global primary energy consumption and is often heralded as the perfect example of the ‘circular economy’ – where waste products can be reused to generate energy for other processes in a self-perpetuating cycle.

Biogas consists of the mixture of gases produced by the breakdown of organic matter by bacteria under anaerobic (oxygen-free) conditions. The exact chemical composition of biogas depends on the feedstocks used, but it is usually around 60 per cent methane and 40 per cent carbon dioxide, with trace contaminant gases. The methane content is particularly valuable as this is what can be burnt to provide energy to be used elsewhere.

In biogas production plants, there are several areas where monitoring methane levels is crucial. For safety and environmental purposes, methane sensors are required throughout the plant to check for unwanted leaks. Methane is a significantly more potent greenhouse gas than carbon dioxide, so fugitive emissions must be avoided and methane also poses health and safety risk for plant workers in terms of its flammability and as an asphyxiant. As a result, UK Health and Safety legislation cover several aspects of methane use in the workplace, including the Dangerous Substances and Explosive Atmospheres Regulations act and the requirement for specific flammable gas detectors.

Process Control

The other key area of the biogas plant that requires accurate and rapid methane monitoring is in the biogas reactors themselves. In the digestor, bacteria break down organic waste matter in the absence of oxygen to form the gaseous mixtures that will later undergo refining. It is crucial that process conditions in the digestors, such as temperature, are controlled very carefully to optimise methane yields and production efficiency.

In order to produce the final biogas product, unwanted gases need to be separated from the high energy-density methane. Here, methane sensors can be used to work out the methane concentrations in the final product before sale.

Edinburgh Sensors

Edinburgh Sensors offers a variety of devices suitable for the online monitoring of methane gas. These are based on nondispersive infrared (NDIR) technologies that provide excellent sensitivity for quantitative and qualitative detection to detect a variety of gases, including methane and carbon dioxide.

Of Edinburgh Sensors’ range, the Gascard NG and Guardian NG are both quick to install stand-alone devices that can be used for online methane monitoring. With only a connection to a reference gas required, they can easily be integrated into existing process monitoring systems to provide robust, real-time data to inform process control and optimisation conditions. For this, both devices offer a R232 interface or, for the Gascard NG, an onboard TCI/IP communications protocol option and the possibility of inclusion of an Ethernet port.

Both the GasCard NG and Guardian NG are ideally suited for methane monitoring as they offer an accuracy of ±2% of range or ±<0.015% of range per mbar.  These gas monitors can be installed in a variety of environments. Measurement accuracy is unaffected over 0 – 95 % humidity ranges and measurements have onboard temperature and pressure compensation over a 800 mbar to 1150 mbar range.

Rapid Quantitative Analysis

All of the Edinburgh Sensors OEM sensors for methane analysis offer rapid detection times for quick diagnosis of any process issues. The Gascard NG has a T90 response time of 10 seconds or < 30 seconds for the Guardian NG. Both devices have initial warm up times of just one minute, and operate at full specification after 30 minutes, so there are minimal delays to starting measurements.

The NDIR source and sensors at the heart of the gas detection systems are designed to be field serviceable for minimal downtime. The Guardian NG also comes with an IP54 rated enclosure, which prevents dust or water from interfering with the functioning of the sensor. This ensures reliable, robust measurements for critical processes and safety at all times.

For safety use, the devices can either be connected to an external alarm system, or in the case of the Guardian NG, there is a built-in alarm with a programmable interface. This interface can also be used to display historical readings as well, though both the Guardian NG and Gascard NG can both be connected to external data logging software. Edinburgh Sensors can supply software with the sensors or, where customers have more complex, individual requirements, custom support is also offered.

The sensitivity of the NDIR gas sensors means even very low methane concentrations can be detected, ideal for leak detection, or small variations in the methane concentration as part of the anaerobic digestion processes. Both devices are capable of detecting 0 – 100 % methane concentrations, making them highly flexible devices.

New ABB emission monitoring solution helps the maritime industry achieve decarbonisation targets

The launch of ABB’s CEMcaptain will help shipping comply with the sulphur emission regulations that were enforced in 2020, and keep in check their CO2 footprint.

In January 2020, the low sulphur and nitrousoxide emission limits in the International Maritime Organisation regulations became effective worldwide. CEMcaptain is a powerful emissions monitoring system from ABB designed to help the maritime industry meet these new regulations and become more sustainable. Its measurement and digital capabilities increase on-board safety, provide process optimisation and substantially reduce ownership costs. By consistently achieving 98 percent and more uptime, the new system not only requires less maintenance effort but also saves time otherwise spent on handling non-compliance issues.

Designed with busy mariners and a regularly changing crew in mind, CEMcaptain is a multi-component analyzer system that continuously provides real-time data offering reliable measurement of emissions with the highest stability. Operating in even the harshest of conditions it integrates analyzer modules and sample handling components in a standalone cabinet, making installation easy.

Equipped with ABB’s renowned Uras26 non-dispersive IR gas analyzer, CEMcaptain simultaneously and continuously measures sulphur dioxide (SO2) and carbon dioxide (CO2) in line with regulation requirements. Each analyzer has two separate gas paths to allow for continuous CO2/SO2 measurement of separate streams, with up to four different components per analyzer module.

“Our solutions are driving the evolution of sustainable shipping, paving the way to a zero-emission marine industry. ABB has more than 60,000 Continuous Emissions Monitoring Systems (CEMS) installed in over 100 countries that help monitor our environment,” said Stephen Gibbons, ABB’s Head of Product Management in Continuous Gas Analyzers. “We draw on 60 years of experience in emissions monitoring to provide this support in concrete terms. CEMcaptain has been combined with innovations in on-site and remote digital services. The result is a solution that provides the industry with a digital toolbox that increases regulatory compliance and operational efficiency.”

Fast fault reporting, diagnosis and repair are achieved via the on-site and remote digital services which help operators get closer to 100 percent availability for their gas analysis instrumentation. Dynamic QR codes are integrated into the ABB CEMcaptain system display panel. All relevant diagnostic information can be collected from the analyzer via a scanned code and transferred to ABB support. This means that maritime instrumentation technicians can send real-time information to an ABB service expert to get immediate guidance on appropriate maintenance. ABB Ability™ Remote Assistance with secured connectivity direct to ABB support is also offered for real-time solutions to problems. These features reduce the costly training of changing crews as well as the number of experts required on board. They also increase on-board safety by reducing crew exposure to emissions.

CEMcaptain GAA610-M is approved by all major classification societies (DNV GL, ABS Group, Lloyds Register, Bureau Veritas, ClassNK, Korean Register).

ABB sensor onboard SpaceX rocket to detect greenhouse gas emissions

ABB and GHGSat collaborating on groundbreaking technology to detect greenhouse gas emissions

An optical sensor manufactured by ABB was deployed with the successful launch of satellite Hugo from GHGSat, the emerging leader in greenhouse gas sensing services in space.

The ABB supplied optical sensor can map methane emissions from space at a resolution that is 100 times higher than any other sensors. Whilst previously only larger regions could be surveyed, for the first time the new greater granularity now allows the identification of the source of emissions. An additional nine units are currently under manufacture at ABB to be launched by the end of 2022 ready to be on-board across the first private satellite constellation dedicated to emission measurement.

Space offers the ideal location to freely monitor emissions across jurisdictions and quantitatively report on improvements. The ABB sensors will provide valuable insights which will enable governments and industries around the world to meet their emission reduction targets and reduce the negative impact on global warming.

“We selected ABB for its ability to deliver world-class instruments while meeting the challenges of a new space company like ours.“ said Stephane Germain, CEO of GHGSat. “We strive to innovate for the needs of the future, and we’re excited to work with ABB to achieve that.”.

“ABB shares GHGSat’s goal of reducing emissions through the creation of their greenhouse gas sensing constellation. Our selection as the manufacturer for these advanced sensors demonstrates our competitiveness and strong fit with the private space sector requirements.” said Marc Corriveau, General Manager ABB Measurement & Analytics Canada.

“The space revolution is well underway and ABB with its heritage of unique space instruments and serial production of advanced measurement sensors for industrial applications is extremely well positioned to serve this emerging sector.” he continued.

GHGSat announced the constellation contract award with ABB in October 2020, with first deliveries in 2021. The unit launched by SpaceX was a single unit procured by GHGSat from ABB two years ago ahead of a selection for the constellation.

With its involvement in the Canadian SCISAT mission and the Japanese GOSAT series of satellites, ABB has been at the forefront of the field of greenhouse gas sensing from space for more than two decades. ABB optical equipment already in space cumulates more than 100 years of reliable operation. The SCISAT sensor tracks long-term subtle composition changes in the earth’s atmosphere down to parts per trillion of more than 70 molecules and pollutants since 2003. Weather agencies across the world base their predictions on ABB equipment flying onboard the US National Oceanographic and Atmospheric Administration (NOAA) weather satellites (NPP and JPSS), which saves lives by improving the timeliness and accuracy of weather forecasts for up to seven days.

ABB is also a global leader in earthbound continuous emission monitoring with over 60,000 systems installed in more than 50 countries worldwide. Continuous Emissions Monitoring Systems (CEMS) continuously record and evaluate emission data across all industries. They provide important information for the environmental and economic operation of production facilities. The range includes the ACF5000 that accurately and reliably monitors up to 15 gas components simultaneously.

Chell Instruments welcomes 2021 after 2020 exceeds expectations

Despite an unpredictable 2020, gas measurement and control experts Chell Instruments still achieved their key goals for the year and are now planning for a successful 2021.

Nick Broadly, Chell Instruments

Though the global pandemic caused disruption, the manufacturer has continued to support a growing number of customers and provide precision instrumentation around the world.

“Coronavirus has made 2020 an unusual year! However, despite the challenges, most projects within key industries like F1, energy and even aerospace have continued unabated. I’m proud to say our team has shown exceptional resilience and gone the extra mile to support our clients with the products and expertise they need” says Chell Instrument’s Managing Director, Nick Broadley.

The world-renowned gas measurement and control experts have maintained momentum throughout the year, achieving the targets set for the business. In addition, they have launched a number of new products including an Environmental Flow Test Chamber and a mini pressure scanner with EtherCAT connectivity.

“Even with the challenges, demand looks set to continue to grow in many sectors in 2021. For example, despite the current restrictions on air travel, we’re really excited that our instrumentation is being used in a number of projects working on the electrification of aircraft propulsion” states Nick.

This month also sees Chell Instruments celebrate their first anniversary as part of the SDI Group of scientific and technology manufacturers. The group now owns more than ten companies which produce products for use in imaging, sensing and control applications.

“Being a part of SDI has given us a new thirst for growth and is helping us to invest in the future. We can pool ideas, experience and resources with our sister companies to ensure we continue developing innovative solutions for new and existing customers” Nick continues.

As Chell Instruments export products to countries around the world, they have welcomed the UK’s new trade deal with the EU. “We are pleased the Brexit deal has been agreed. As we sell to Asia and North America, as well as Europe, we have plenty of experience with the custom checks, processes and paperwork necessary. However, the deal means we can go on delivering UK technology to Europe with ease and without extra cost to the customer” concludes Nick.

Established over four decades ago, Chell Instruments produce pressure, vacuum and gas flow measurement and control solutions for use in industries including energy, pharmaceuticals, Formula 1 and aerospace.

The firm’s 2021 plans include continual development of their ultra-compact range of ‘Nano’ pressure measuring devices and a special project to deliver a self-contained mobile testing unit for a leading aircraft engine manufacturer.

To learn more about Chell Instruments visit www.chell.co.uk.

New ScioSense gas sensor achieves industry’s closest match to natural human response to impaired air quality

The new ENS160, an indoor air quality sensor launched today by ScioSense, uses sophisticated sensor fusion algorithms to produce measurement outputs which are better tuned to the natural response of human occupants than any other sensor on the market provides.

ScioSense, a manufacturer of integrated environmental and flow sensors, has implemented a new multi-element sensing architecture for its next generation of air quality sensors using four highly integrated MEMS micro-hotplates, and developed sensor fusion technology which synthesises the signals from each sensing element while compensating for the effect of humidity.

This new technology underlies an industry-best Automatic Baseline Correction function, which intelligently resets the local threshold for air quality to ensure that the ENS160 reliably detects changes to pollution levels and odours in indoor air, no matter where in the world it is located. Intelligent sensor fusion is also the key to an enhanced carbon dioxide equivalents (eCO2) score, which takes account of the range of polluting or odorous gases generated by human activity in addition to exhaled CO2.

These advanced features, unique to the ENS160, mean that its air quality indicators much more closely reflect the effect of airborne pollutants and odours on occupants of indoor space. Systems such as air purifiers, demand-controlled ventilation, cooker hoods and smart home hubs based on the ENS160 can perform more accurate monitoring of indoor air. This means that users can enjoy clean and fresh air at all times while avoiding the waste of money and energy incurred when running air-cleaning equipment unnecessarily.

The new micro-hotplates and intelligent operating controls also provide high immunity to contamination by siloxanes, ensuring a long operating lifetime in any indoor residential, commercial, professional or in-cabin automotive setting.

Dirk Enderlein, CEO at ScioSense, said: ‘When ventilation or air-cleaning equipment stops running because the air-quality monitoring system has failed to detect human body odours, or has its baseline for air quality set too high, it has a real effect on the occupants of indoor spaces. It impairs the ability of school students to focus on their lessons, it puts people at risk of long-term harm caused by pollution, and it makes our living spaces less pleasant to work or relax in. Offering a unique combination of high broadband gas sensitivity and intelligent selectivity, the ENS160 enables ventilation and air cleaning systems to be used in the right way at the right time, to improve the quality of life for people indoors.’

Three types of accurate air quality output

The multi-element technology on which the ENS160 is based is sensitive to oxidising gases such as ozone which affect the quality of indoor air, as well as to a wide range of volatile organic compounds (VOCs) such as toluene, ethanol, methane, sulfur dioxide and carbon monoxide. The algorithms supplied with the ENS160 produce three measurement outputs:

  • Total VOCs (TVOC), which draws on the broad sensitivity of the ENS160 to human-generated and artificial VOCs
  • eCO2, a commonly used proxy measurement for the density of human occupation of an indoor space
  • Various air quality indexes which are compatible with international standards

The ENS160 also provides its raw gas measurements for OEMs which want to apply proprietary algorithms.

The sensor is housed in a surface-mount package which measures just 3mm x 3mm x 0.9mm, making the ENS160 the smallest fully integrated, reprogrammable air quality sensor in the market, suitable for integration into highly space-constrained designs, including in consumer products.

The ENS160 provides its measurement outputs to a host controller via a serial peripheral or I2C interface. Since all the sensor’s measurement algorithms run on-chip, there is no processing overhead on the host.

ScioSense also supplies an analogue version, the ENS145, which is based on the same micro-hotplate technology that the ENS160 uses. It is intended for distributed system designs in which a central host fully controls the measurement outputs derived from the gas sensor inputs that the ENS145 provides.

Product samples and evaluation kits will be available on request from ScioSense and authorised distributors in Q1 2021.

What is fresh air and is it really fresh?

Covid-19 is a highly contagious disease and to mitigate the spread of the virus especially indoors, the common refrain is to make sure the space is well ventilated with fresh air. But what exactly is fresh air? Fresh air is typically defined as cool, unpolluted air in natural surroundings. But as there is no agreed parametric definition of what fresh air is, how can you determine if the air indoors is really fresh?

Although the World Health Organisation (WHO) has not formally confirmed that COVID-19 is spread by airborne transmission, it is probably only a matter of time as other similar viruses such as norovirus and the flu are acknowledged to be spread in this way. In the case of COVID-19, it is believed that ventilation plays an important part in reducing transmission by dilution and removal of infected particles and droplets.

Ventilation is the intentional introduction of fresh air into a space while the stale air is removed. It is done to maintain the quality of air in that space. According to The American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASGRAE), acceptable interior air quality is where there are no known harmful contaminants in harmful concentrations. But what constitutes harmful contaminants in harmful concentrations is left to individual States to define, such as the Title 14 California code of regulations, which stipulates for example maximum permissible levels of CO2 in a building.

In the UK, there are guidelines such as the Building Regulations 2010 for manufacturers, architects and engineers involved with building design and services to assist in the process of reducing poor air quality and ensuring there is enough fresh air ventilation. The Health and Safety at Work etc Act 1974 is the primary piece of legislation covering occupational health and safety. It states that employers have a duty of care to ensure there is a safe and healthy work environment. New and revised workplace exposure limits (WELs) came into force from January 2020 under the auspices of the Health and Safety Executive EH40/2005 containing an updated list of maximum exposure limits and occupational exposure standards for specific gases as required by the Control of Substances Hazardous to Health (COSHH) Regulations.

However, there are currently no regulations on what constitutes ‘good quality’ indoor air. Although there have been calls on the Government to make measuring and monitoring of indoor air quality a legal requirement in commercial buildings and schools especially in urban locations, legislation has not yet been forthcoming.

The established benchmark test for indoor air quality is to assess CO2 levels. Ignoring particulate matter, VOCs and other contaminants, it is generally understood that indoor CO2 levels are a good proxy for the amount of pollutant dilution in densely occupied spaces and can therefore be used as a good indicator for fresh air.

So how do CO2 levels equate to fresh air? The amount of carbon dioxide in a building is usually related to how much fresh air is being brought into the building. In general, the higher the concentration of carbon dioxide in the building in comparison to outdoors, the lower the amount of fresh air exchange. The background level of CO2 outdoors is generally considered to be in the range of 350-450 parts per million (ppm). CO2 is a by-product of normal human activity and is removed from the body via the lungs in the exhaled air. Unless an indoor space is adequately ventilated, CO2 will naturally build up over time. CO2 levels in a well managed indoor space are generally 350- 1,000ppm. Above 1,000ppm and most people will begin to complain about the stuffy atmosphere or poor air quality. High levels of CO2 indoors are also associated with headaches, sleepiness, poor concentration, and loss of attention and in extremely high concentrations, CO2 is harmful to life due to oxygen deprivation.

CO2 sensors along with temperature and humidity sensing are often used as part of automatic ventilation control systems. But what if the building or school does not have such a sophisticated environmental control setup?

Ample natural ventilation is considered to be the best method to prevent the Sars-CoV-2 virus from spreading indoors. The amount of fresh air that needs to be supplied is a matter of conjecture, but good practice is to ensure ventilation is capable of keeping CO2 levels below 1,000 ppm or even lower. Assuming monitoring of CO2 levels is a good proxy for fresh air, CO2 sensors can be used to check if there is enough ventilation in the building and if not, to trigger a response. At its simplest, this can be as simple as setting a CO2 alarm level to prompt opening a window in the room.

Most high-performance ambient level CO2 sensors use a measurement method called Nondispersive Infrared (NDIR), where the CO2 level is determined using the Beer-Lambert law. Beer-Lambert’s law states that the loss of light intensity when it propagates in a medium is directly proportional to intensity and path length. CO2 molecules absorb infrared radiation at a wavelength of around 4.25 microns.

CO2 monitoring systems often need to be installed in locations where access to mains power is limited, or its provision is costly. The ability to be able to power the CO2 sensor for long periods of time from a battery or from energy generated using harvesting techniques is highly desirable. To reduce maintenance costs, users want the ability for the CO2 sensor to operate autonomously for many years without user intervention.

Conventional CO2 sensors use an incandescent light source. However, these mid-IR light sources consume lots of power during a lengthy warm-up phase and during operation, making them unattractive especially for retrospective installations, where there is often a lack of an easily accessible power source.

All GSS sensors use an in-house designed ultra-efficient LED light source. LEDs are much more efficient in converting electrical power into light than conventional light sources and they do not need the long warm-up times suffered by incandescent light sources. The length of time the light source is active is a significant contributor to how much power is consumed by the sensor. In a power-sensitive application, a GSS CO2 sensor is typically pulsed on and off to minimise overall power consumption.

Depending on installation requirements, a CO2 monitor can range from a simple display on the wall with a programmable alarm to sophisticated systems with wireless interfaces sending data up to the cloud.

The latest GSS sensors such as the CozIR-Blink are designed to operate in battery-powered units so they can be easily installed and deployed. They are designed to be power cycled, where the whole device is powered down after a CO2 reading has been made. A typical installation might be preprogrammed to take one reading every few minutes. Depending on the required CO2 measurement accuracy, if the sensor is configured to take a reading every minute, the power consumed by the CozIR-Blink can be as low as 26uW per reading. Whilst obviously dependent on what other electronics are in the sensor, CO2 monitors using the CozIR-Blink are often designed to last for two or more years on a single battery charge.

All GSS sensors can also be pre-programmed to run an automated background ‘reference-setting’ routine where CO2 levels are monitored over time. The reference value is the lowest concentration to which the sensor is exposed over an extended period such as a week and is typically considered to be the fresh air minimum ambient level. This scheme allows users to set an alarm threshold that is relative to a fresh air reference value, which takes account of changing outdoor ambient CO2 levels. The sensor programable alarm can easily be used to drive a “traffic light alert” indicating it is time to open the window.

Ultra-low-power sensors such as the CozIR-Blink open-up new installation possibilities in a wide range of offices, workplaces and schools. Used correctly, this type of CO2 sensor can be employed as a simple and cost-effective tool to help avoid catching the virus indoors.

Find out more: https://www.gassensing.co.uk/