Gas sensing

MOFs can sense and sort troublesome gases

From astronauts and submariners to miners and rescue workers, people who operate in small enclosed spaces need good air quality to work safely and effectively. Electronic sensors now developed by a KAUST team can simultaneously detect at least three critical parameters that are important to monitor to ensure human comfort and safety.

MOFs can sense and sort troublesome gases. Credit: 2019 KAUST

These new sensors use fluorinated metal-organic frameworks (MOFs) as the sensing layer. MOFs are porous materials comprising a regular array of metal atoms held together by small organic-molecule linkers to form a repeating cage-like structure. KAUST’s Mohamed Eddaoudi, who led the two studies of the sensor’s efficacy, explains that by altering the metal and organic components, MOFs can be tuned for applications ranging from gas separation and storage to catalysis and sensing.

“Many people have attempted to develop simple, efficient, low-cost SO2, CO2 and H2O sensors without success,” say researchers Mohamed Rachid Tchalala, Youssef Belmabkhout and Prashant Bhatt, all from Eddoudi’s lab.

The approach taken by Eddaoudi’s group was to develop a fluorinated MOF, which Belmabkhout and Tchalala tested as sensor materials for these gases. Testing of these state-of-the-art materials was in collaboration with Khaled Nabil Salama and his team.

The first study shows how the sensor can measure the concentration of carbon dioxide and the level of humidity in the air. While the second study of the same fluorinated MOFs shows it can detect the harmful and corrosive gas sulfur dioxide, or even selectively remove it from powerplant flue gas.

“Traces of SO2 are invariably present in the flue gas produced by factories and powerplants, and SO2 can poison materials developed to trap CO2 for carbon capture and storage,” say Belmabkhout and Bhatt. “AlFFIVE-1-Ni can soak up SO2 with an affinity 66 times higher than for CO2, while showing good stability to SO2 exposure.”

The MOFs could also be used with two simple, low-cost high-sensitivity sensor platforms. Quartz crystal microbalance (QCM) sensors that are coated with a thin film of either MOF detected the change in mass with the absorption of SO2, or water and CO2. Similarly, MOF-coated interdigitated electrode sensors detected a change in electronic properties with the absorption of water and CO2.

Both sensor platforms, the team showed, could monitor moisture and CO2 levels under real atmospheric conditions. “The signal is calibrated against CO2 concentration, humidity level and mixtures of both,” Tchalala explains. A QCM-based sensor could also detect SO2 in the air at levels of just 25 parts per million.

ABB helps improve safety and profitability of oil and gas pipelines with drone-based gas leak detection

Leaks in gas distribution and transmission pipelines present serious safety risks and result in lost revenue and profits to producers.  The ABB Ability mobile gas leak detection system is a digital solution that for the first time, enables drone deployment in the identification of gas leakages. The new solution is being launched at ABB’s customer event in Houston to complement the existing range of ABB mobile gas leak detection systems suitable for all facilities.

The ABB Ability mobile gas leak detection system benefits from drone deployment as it enables faster identification of leaks, requires less man hours to implement and costs less to operate as it covers wide, hard-to-reach areas. To avoid false readings, it can distinguish between biogenic methane, the source of which is ruminant animals, manure and shallow coal and oil deposits, from thermogenic methane from natural gas.

The solution uses patented cavity-enhanced absorption spectroscopy to detect methane and ethane with a sensitivity more than 1000 times higher than conventional leak detection tools. Particularly robust yet simple, the Off-Axis Integrated Cavity Output Spectroscopy (OA-ICOS) has extreme sensitivity that allows ABB to quickly identify potential methane emissions at a greater distance while flying, which is not possible with other sensors.

ABB’s analysis software automatically processes the collected methane, ethane, GPS and wind data to create a simple, easy to use report in either GIS compatible or PDF formats. These reports can be used to quickly identify areas in the pipeline network that potentially have leaks.

Additionally, the software features, such as the ABB Ability cloud storage tools, allow quick and efficient distribution of data and reports to all stakeholders anywhere in the world. Authorised users can view the progress of flights in real-time as well as review and act on processed leak reports.

In March 2018, ABB was one of six companies invited by the Environmental Defense Fund (EDF) and Stanford University to represent the drone sector in the controlled testing phase of the Mobile Monitoring Challenge (MMC), a competition to advance mobile methane monitoring technologies at oil and natural gas facilities.

As well as being used for drones, the ABB Ability mobile gas leak detection system is used in urban distribution vehicles and hand held inspection devices, meaning that all three methods of gas detection can be deployed in conjunction with one another to provide optimal safeguarding of both people and the environment.

FLIR launches its first uncooled methane gas detection camera

FLIR Systems has announced the FLIR GF77 Gas Find IR, its first uncooled thermal camera designed for detecting methane. This handheld camera offers inspection professionals the features they need to find potentially dangerous, invisible methane leaks at natural gas power plants, renewable energy production facilities, industrial plants, and other locations along a natural gas supply chain. The GF77 provides methane gas detection capability at roughly half the price of cooled gas inspection thermal cameras, to empower the oil and gas industry to reduce emissions and ensure a safer work environment.   

Based on the award-winning design of the FLIR T-Series camera platform, the lighter weight GF77 features an ergonomic design, a vibrant LCD touchscreen, and a viewfinder to make it easy to use in any lighting conditions. The camera is engineered specifically to detect methane in order to improve gas inspections and reduce the chance of false readings. The GF77 also offers FLIR’s patented High Sensitivity Mode (HSM), which accentuates movement to make tiny gas plumes more visible to the user.

FLIR designed the GF77 to include its most updated technological features, including laser-assisted autofocus to help inspectors target leaks better, and one-touch contrast improvement that makes gases stand out clearly against the background. Additionally, a rapid-response graphical user interface helps professionals increase efficiency by allowing them to organize job folders, record notes, and add GPS location annotation on the camera.

“Optical gas imaging technology is a real benefit to industries that use or produce methane, but the cost of the technology has been a barrier for some customers,” said Jim Cannon, president and CEO of FLIR Systems. “The FLIR GF77 Gas Find IR gas detection camera is built around an uncooled, longwave infrared detector, which costs less to produce than our higher performance, cooled cameras, and therefore we can provide it to customers at a more attractive price point. By providing the industry with access to this groundbreaking technology, we can help improve the safety of professionals on the job.”

Drone inspection for gas detection

Gas sensors for the detection and monitoring of harmful substances within the environment such as carbon monoxide, carbon dioxide and methane are essential elements of environmental risk assessment.

Used in a wide range of industries, processes and applications they touch our every day lives monitoring toxins found in landfill and agriculture right down to modified atmosphere packaging. But what do you do when faced with monitoring gas levels in areas where no man should go? This is the issue which presented itself to Edinburgh Sensors‘ clients, NTCR Consulting.

NTCR are NASA contractors who specialise in the field of harsh environment technology. Tasked with helping a customer conduct volcanic research they had to find a solution to help them navigate and conduct their research in an area which was difficult to access and inhospitable. A gas sensing drone was the answer. As an unmanned aerial vehicle (UAV) this provided a versatile solution to access this hazardous and potentially contaminated terrain.

With an emphasis on CO2, H2S and SO2 a gas sensing drone was developed with enhancements including sensor options for CH4 and O3. The device included one of Edinburgh Sensors’ own high sensitivity laser diodes with the additional option of up to four electro-chemical sensors. The sensors can be customised to a variety of specifications for species and sensitivity ranges.

Volcanic Drone Inspection, Italy

You can watch the UAV drone inspection test of the NTX minigaps Instrument Solfatara and Vulcano Deployment conducted in Italy below.

Solutions for Gas Sensing

Edinburgh Sensors have a range of gas sensors to suit a variety of gases. Manufactured to the highest specification, they can be integrated into a wide range of systems for fast and reliable measurements of CO, CO2 and CH4. The company is able to provide bespoke solutions to meet research and technical requirements suitable to a wider range of gases.

Gas Sensing Solutions investigates levels of CO2 on car journeys

Ever wondered why long car journeys make you feel tired and sleepy? Is it the boredom of endless, never changing motorways or perhaps something else? Carbon Dioxide sensor specialists, Gas Sensing Solutions, wondered if it could be a build-up of CO2 gas because, at levels of 1,000 ppm and above, people can become drowsy and lethargic. So they took a CO2 datalogger from their gas sensor range on a road trip to find out how CO2 levels changed throughout the journey.   

Dr David Moodie, technical manager at GSS, explained, “This follows on from our trip to Asia where we used our CO2 datalogger to measure CO2 gas levels on planes, trains and taxis. We were surprised that levels were the worst in taxis – peaking at an astonishing 10,000 ppm on one journey – so we decided to check the levels on our own road trip in the UK.” 

Before the datalogger took to the road, it was first used to test CO2 levels in a stationary car. This would show the impact on CO2 levels with a group of four people in a confined space. The engine was switched off and the windows kept closed to avoid any flow of fresh air inside the vehicle. The datalogger showed that when the passengers got inside the car, the CO2 level was 1,000 ppm. It then rocketed to almost 4,000 ppm in just 15 minutes. At that stage, the atmosphere inside the cabin had become extremely stuffy and unpleasant.

Next came the road trip. The first car journey involved two people travelling to the supermarket. The CO2 from their exhaled breath increased the concentration of CO2 in the car cabin to around 1,400 ppm. Surprisingly, it only took about forty-five minutes to reach this level, which shows how quickly CO2 levels can rise. The datalogger was then left in the car overnight with the windows closed. The graph shows just how long it takes for the CO2 to disperse from a closed car, taking until around 9am the next day to drop down to nearer ambient levels of CO2.

The second car journey recorded four people travelling non-stop from Wales to Scotland. With four people, the level of CO2 shot up even faster, reaching 2,000 ppm in about twenty minutes. This is the level where CO2 symptoms can start to cause loss of concentration, headaches and sleepiness for example. Fortunately, they opened the windows to bring in fresh air from outside, which reduced the CO2 to more acceptable, ambient levels within an hour. 

Moodie added, “Our real-world datalogger measurements show how CO2 levels can rapidly build up in an enclosed space with several occupants – and in a relatively short space of time too. The results on both journeys exceeded The World Health Organisation guideline that CO2 levels should be below 1,000 ppm.”

Datalogger details

The datalogger used in the experiment measures CO2 concentration, air pressure and temperature, along with relative humidity every few minutes. This unit was designed and built by GSS and it uses one of its low power, ambient air, CozIR-A sensors. GSS’s unique LED technology at the heart of its sensors means that it has a very low power consumption, unlike many other CO2 sensors that need mains power. This enables battery-powered CO2 monitoring products to be created, such as this datalogger, that is able to record over a two-week period without needing a change of battery. Moodie concluded, “This ability to be battery powered for long periods has opened up a whole new range of design possibilities for CO2 monitors. Now it’s possible to have handheld breath monitors with high speed sensing for people with respiratory conditions, portable leak detection instruments, handheld MAP analysers, and wireless air quality monitors for IoT applications. These are just a few examples of what is achievable, the possibilities really are endless.”

Drowsy driving facts and stats 

According to a 2005 poll by the American National Sleep Foundation, 60 per cent of adult US drivers – about 168 million people – said that they have driven a vehicle while feeling drowsy in the past year. More than one-third, (37 per cent or 103 million people), have actually fallen asleep at the wheel. Of those who have nodded off, 13 per cent say they have done so at least once a month. According to data from Australia, England, Finland, and other European nations, drowsy driving represents 10 to 30 percent of all crashes.

Ultrasensitive toxic gas detector

Researchers from the School of Microelectronics in Tianjin University have discovered a two-step sputtering and subsequent annealing treatment method to prepare vertically aligned WO3-CuO core-shell nanorod arrays which can detect toxic NH3 gas.

A schematic illustration of the gas sensor device based on the hybrid nanorod arrays. The real time resistance versus time of the vertically aligned WO3-CuO core-shell nanorod arrays-based gas sensor to varied concentrations of NH3 decreasing from 500 ppm to 50 ppm at 150 ?. The resistance of the WO3-CuO hybrid increases upon exposure to NH3, consistent with p-type semiconductor behavior. The response of the hybrid sample increasing with increasing NH3 concentration at 150. The response and recovery times range from 10 to 15 s for all NH3 concentrations.

Over the years, WO3 has received considerable attention among the numerous transition metal oxides as a wide band-gap n-type semiconductor in various gas detection, such as NOx, H2S, H2, and NH3. CuO has the unique property of being intrinsically p-type. In the last decade, p-n heterojunction sensors composed of an n-type metal oxide and CuO were reported to have a good sensitivity to reducing gases owing to the interface between n-metal oxide and CuO. Much effort has been focused on the WO3-based nanocomposites, since the synergetic enhancement and heterojunction effects attributes to the enhanced gas sensing properties. However, gas sensors based on 1D WO3-CuO composite structures are limited. Additionally, the template or catalyst was usually necessary to synthesize WO3-based nanorod arrays, including using chemical vapor deposition, electrochemical anodization and hydrothermal approaches.

Among toxic gases causing adverse impact on living organisms, NH3 is one of the most hazardous substances. It is necessary to build up ultrasensitive NH3 gas sensors with short response and recovery time. Metal oxides have been widely used in gas sensor applications. In order to obtain great sensing performances of metal oxide sensors, 1D metal oxide nanostructures and 1D heterojunction composite nanostructures have been investigated due to their large surface area, size-dependent properties, and the nano-heterojunction effects. Vertically aligned ordered 1D arrays effectively avoid the dense stacking of rod monomers, especially, resulting in novel physicochemical characteristics, such as higher gas response and shorter gas recovery.

Here, vertically aligned WO3-CuO core-shell nanorod arrays are synthesized using a non-catalytic two-step annealing process of sputtered metal film on silicon wafer. The growth mechanism of the vertically aligned nanorod arrays are discussed. The NH3 sensing behaviors of the WO3-CuO core-shell arrays at different temperatures are reported. A possible NH3sensing mechanism for the hybrid is proposed.

JBS&G adds another Tiger PID to portfolio of gas detection instrumentation

Australian environmental consultancy, JBS&G has purchased another well-proven Tiger handheld volatile organic compound (VOC) monitor from Ion Science.

This latest handheld photoionisation detector (PID) is being used on a major new project and was chosen for a number of performance benefits as well as the free extended five year warranty.

JBS&G is one of Australia and New Zealand’s leading and most respected providers of environmental services, including contaminated land, groundwater remediation, impact assessment, due diligence, EPA accredited auditing, hazardous materials and occupational hygiene assessment. The company has worked on some of the largest and most complex environmental assessment and remediation projects in the countries.

Aaron Smith, senior consultant at JBS&G, commented: “We use PIDs on a daily basis to help implement our many contaminated land projects. The company owns several VOC monitors, including Ion Science instruments, and often rents extra ones too to cope with the ebb and flow of business. We have been using the handheld Tiger detector for many years without a problem and found it to be a robust, reliable, fast, accurate and user-friendly solution.

He continued: “A major new project prompted the need for a further PID and we did not hesitate in choosing another Ion Science Tiger especially with the free five year warranty when the instrument is registered within one month of purchase.”

Ion Science’s Tiger is being used by JBS&G to detect the presence of airborne concentrations of VOCs emitted from soils contaminated by petroleum hydrocarbons and other substances. The results are interpreted and used to assess potential health risk to site workers and the surrounding members of the public.

JBS&G’s uses the Tigers to monitor VOCs in a wide variety of applications, including contaminated soils (headspace and soil vapour), surface water, groundwater, unknown chemical compounds, under and above ground petroleum storage tanks, abandoned buildings, service pits, sewers, as well as other confined spaces.

JBS&G benefits from multiple PIDs within its business across all states of Australia. They are used on a daily basis during contaminated land investigations and other assessments of potential hazardous substances. Data is manually recorded on score sheets or downloaded to a PC where formal reporting is required.

The Tiger’s PID sensor utilises advanced patented Fence Electrode technology, a three-electrode format with increased resistance to humidity (up to 99 per cent RH) and contamination. This maximises accuracy and dependability by removing high backgrounds and false-positives in high-humidity environments. The anti-contamination design also reduces calibration frequency.

Aaron added: “We use the PID to assess potentially contaminated land, air and materials which makes the Tiger’s anti-contamination design very important in providing the most accurate results possible.”

The Tiger incorporates the recently released MiniPID 2 sensor, which offers a raft of benefits to instrument functionality, including reliable operation at extreme temperatures and more repeatable performance.

Other advantages of the MiniPID 2 are lower running current, robust lamp illumination and more reliable operation at extreme temperatures.  It gives stability, control and reliability benefits that are unavailable in other PID designs.

The Tiger is designed for rapid detection, with an unrivalled response time of just two seconds, and the widest measurement range of one part per billion (ppb) up to 20,000 parts per million (ppm).

It offers worldwide Intrinsic Safety (IS) certification and also meets ATEX, IECEx, North American and Canadian standards. Inexpensive disposable parts such as filters and lamps are easy to change, minimising downtime. Simple connectivity to a PC via the USB allows data to be downloaded quickly.

“The overall service from Ion Science has been excellent and we will definitely be using more of their monitoring instruments in the future,” Aaron concluded.

How to use infrared technology for gas detection

FLIR Systems, through its Infrared Training Centre (ITC), has announced a live online tutorial on 25 May 2017 that addresses the subject ‘Discover how you can use infrared technology for gas detection’.

Presented by Steve Beynon, a leading specialist with over 10-years experience of optical gas imaging, this live online tutorial will provide an overview of how infrared technology is successfully used for gas leak detection. Attendees will learn what type of infrared camera is needed, be given examples of gases that can be identified as well as discussing environmental conditions required, safety considerations, and much more.

A basic overview of thermal science will also be given to demonstrate how this application works. In addition, the tutorial will address what users of this technology can do to get the most out of their equipment.

Register here for this free live tutorial session.

The Infrared Training Center (ITC) is the training arm of FLIR Systems. ITC infrared certifications are globally recognized and are designed to exceed the requirements of international infrared thermography certification standards. The staff of ITC participate in infrared certification committees to ensure that they are aware of the latest developments in international standards.