Air quality sensor.

The SGP41 VOC+NOx sensor for indoor air quality applications is supplied by Sensirion. The sensor is designed as a digital smart switch and regulation unit for air treatment devices such as air purifiers.

“This sensor platform enables the simultaneous measurement of both volatile organic compounds and nitrogen oxides, and therefore responds to the growing awareness of the importance of good indoor air quality and the stricter requirements for these applications. With the SGP41, Sensirion aims to further improve indoor air quality and help to protect our health and well-being,” says Dr. Oliver Martin, their Product Manager for Gas Sensors.

 Good air quality is an important component of a healthy indoor environment because indoor air pollution can have harmful impacts on our health. There are many potential and common dangers found in indoor air, such as VOCs (volatile organic compounds), which are typically found in building materials, furniture and cleaning products, among others, and are emitted by humans, and NOx (nitrogen oxides), which are a by-product of combustion. Exposure to these pollutants can be limited by ensuring that enclosed spaces have sufficient ventilation. In addition, air treatment devices are used to eliminate harmful gases in indoor environments and thus avoid unhealthy situations. Equipped with Sensirion’s new SGP41, air purifiers become smart by reliably monitoring VOCs and NOx at all times and removing these gas emissions automatically when the appropriate filters are installed.

The VOC+NOx sensor offers a solution for two complete sensors on a single chip, facilitating design-in and cutting design costs. By relying on Sensirion’s proven MOXSens® Technology, the sensor’s unmatched robustness against contamination by siloxanes results in outstanding long-term stability in terms of sensitivity and response time. The two sensor signals processed by Sensirion’s powerful Gas Index Algorithm can be used directly to automatically trigger the removal of indoor air gas pollutants by air treatment devices without the need for user-device interaction. This sensor solution is thus well-suited to the constant monitoring of VOC and NOx levels, including potentially harmful events that are imperceptible to humans. Furthermore, automatic control of air treatment devices based on the SGP41’s signals helps to save energy by turning them off once the VOC and/or NOx events have received attention. 

#Sensirion #Pauto #HVAC #Environment 

Controlling nitrogen oxide emissions.

Ensure mandated availability and data quality of Continuous Emissions Monitoring System (CEMS) while reducing operating costs.

Environmental regulations are changing at a rapid pace, but many emissions monitoring systems are still operating with obsolete instrumentation, increasing system availability risk, non-compliance penalties, operating costs and shutdowns. It is becoming even more critical for plant operators to select the right technology to keep pace with increasingly stringent emissions regulations.

Nitrogen oxides (NOₓ) emissions remain particularly very challenging for combustion processes. This free eBook examines new gas analysis technologies for monitoring the concentration of NOₓ in gas emissions to help you not only comply with regulations, but also control and optimize combustion processes and better manage energy usage.

This eBook from Emerson teaches

• Use the right gas analysis technology to optimize NOₓ emissions monitoring and reduce operating costs • Ensure mandated availability, performance and data quality of your Continuous Emissions Monitoring System (CEMS) • Leverage the integrated analytics of modern gas analyzers to improve reliability and simplify decision making • Build value creation into environmental compliance by using measurement data from gas analyzers to reduce energy consumption and costs • Get insights into how customers have succeeded in leveraging new gas analysis technologies to achieve more precise emissions measurement and prove full compliance

@EMR_Automation #PAuto

NOx measurement in combustion products & processes.

The need for monitoring NOx and  the factors behind the choice of technology. 

NOx is a generic term for the oxides of nitrogen that have significant effects on the environment and human health. These include nitric oxide (NO) and nitrogen dioxide (NO₂), which are mostly produced by the combustion of fossil fuels such as in vehicles and engines, as well as industrial processes such as power generation and cement manufacture. Consequently, NOx measurements are vital to minimise emissions and demonstrate compliance in applications such as engine development, combustion control, emissions abatement, stack testing, and in the development of any products or processes that burn hydrocarbon fuels. Examples include process boilers, gas turbines, stationary diesel engines, domestic boilers and wood burners.

Why are NOx emissions a problem?
Globally, a wide variety of organisations have published reports linking serious health effects with short- and long-term exposure to NO₂. For example, in 2015, the British Committee on the Medical Effects of Air Pollutants (COMEAP) reviewed the available evidence and concluded: Studies have shown associations of NO₂ in outdoor air with adverse effects on health, including reduced life expectancy. It has been unclear whether these effects are caused by NO₂ itself or by other pollutants emitted by the same sources (such as traffic). Evidence associating NO₂ with health effects has strengthened substantially in recent years and we now think that, on the balance of probability, NO₂ itself is responsible for some of the health impact found to be associated with it in epidemiological studies.

From an environmental perspective, NOx gases contribute to the formation of smog and acid rain, and NOx in the atmosphere contributes to nutrient pollution in coastal waters. Globally, emission limits for NOx are becoming more stringent as governments seek to address these concerns.

NOx measurement in product development
The designers of engines, boilers, turbines and incinerators seek to optimise combustion efficiency whilst minimising the harmful emissions of gases such as NOx. In many cases, this means that products have to be designed to comply with the local emission regulations, wherever they are sold.

Organisations conducting combustion research have a different monitoring requirement to plant operators and stack testers. This is because stack testers simply require analysers that comply with certain performance requirements, whereas those in R&D require highly accurate, definitive measurements of NO, NO₂ and NOx in order to fine-tune their designs and optimise the performance of their products. In addition, it will frequently be necessary for them to provide defensible measurement data in order to secure formal approvals in local markets. This is extremely important because the untimely discovery of any NOx measurement errors, interferences or excessive levels of uncertainty could prove costly.

Reference Method – chemiluminescence (CLD)
The European Standard EN 14792 specifies chemiluminescence as the standard reference method (SRM) for the measurement of NOx in stationary source emissions. However, the method cites several alternative CLD configurations but it only stipulates Chemiluminescence as the method of detection. The Standard does not specify whether the analyser should be heated or unheated, or whether the detector should be vacuum based or atmospheric. In addition, it does not specify whether the NO₂ component should be converted to NO prior to any water in the sample being condensed for removal. The EN standard reference method EN 14792 is intended for stack testing laboratories, to verify the installation of a Continuous Emissions Monitor on an industrial chimney stack.

Designing a true reference analyser - key considerations

1. Chemiluminescent photon detector The chemiluminescence reaction of Ozone and Nitric Oxide causes the oxidation of Nitric Oxide (NO) to Nitrogen Dioxide (NO2) which generates photons that are measured using a photomultiplier tube. To obtain maximum sensitivity from the photomultiplier tube it must be cooled so that its ‘dark current’ can be reduced (dark current is a small electric current that flows even when no photons are entering the device). It would be possible to increase the sample flow to the detector to increase its sensitivity, but it is necessary to keep the sample flow as low as practicable to achieve the quenching target. Typically, at Signal Group, the flows of Ozone and sample are set in a ratio of 10:1. Signal’s CLD instruments employ two detectors for continuous measurements of NO and NO2. The sample is passed directly to one of the detectors, and via the NO2 converter for the other. The NO2 value is derived by continuously subtracting the NO-only detector signal from the other detector’s signal. The reaction chamber design is particularly important with a vacuum based analyser because the reaction gases pass very quickly to the vacuum pump. 2. Advantages of a vacuum CLD Water vapour and Carbon Dioxide within a sample will reduce, or quench, the reading of NO, and combustion exhausts usually contain high levels of both. Signal Group has therefore developed a CLD with a vacuum in the reaction chamber, which eliminates the quenching effect, and increases the signal to noise ratio considerably. An additional advantage of the vacuum is that it allows for the delivery of a hot wet sample gas to the reaction chamber without the threat of condensation. 3. Ozonator design Ozone is necessary for the oxidation of NO, but a number of potential pitfalls exist in the choice of ozone generation technology. For example, high-voltage corona discharge lamps would oxidise any Nitrogen in the air feed to NO and NO2 artificially raising the readings and presenting a threat of corrosive Nitric Acid formation. This could be resolved by using pure Oxygen as the feed gas, but that would be prohibitively expensive. Signal Group therefore employs a soft-discharge neon lamp in its ozonator, which does not oxidise Nitrogen. 4. NO2 Converter The choice of NO2 converter material is an important consideration because at high temperatures stainless steel would oxidise any Ammonia in the sample to NO. Furthermore, if there is insufficient oxygen in the sample, it will be ‘robbed’ from NO2, so an oxygen bleed to the sample would be necessary. To avoid this unnecessary complication, the Signal Group CLD analysers use a vitrified type of carbon in a heated quartz vessel which has none of these characteristics, and lasts for at least two years of operation. 5. Vacuum pump Traditional oil filled rotary vane pumps are prone to problems caused by Ozone contaminating the oil. Signal Group therefore employs membrane pumps with a catalyst for removing Ozone.

With over 30 years of experience in the design and manufacture of reference CLD analysers, Signal Group has continually refined its product offering to ensure the highest levels of accuracy, sensitivity and repeatability. Recognising Signal’s experience and expertise in NOx analysis, James Clements, Signal Group MD, is now a member of the SAE E-31 Aircraft Exhaust Emissions Measurement committee.

In addition to the advantages of Signal’s core CLD technology, recent developments have included functionality enhancements such as compatibility with 3G, 4G, GPRS, Bluetooth, Wifi and satellite communications. Each instrument now has its own IP address and runs on Windows software; providing users with simple, secure access to their analysers at any time, from anywhere.

The most recent development is an option for a detachable screen. Customers will find this useful when it is necessary to install the analyser in a location with difficult access – such as: in an ATEX enclosure; in vehicle exhaust gas test cells; with a raised gantry on a stack; in a combustion test rig, or on any site where the location of analysis is not an ideal or safe working space.

@GasAnalysers @_Enviro_News #NOx #Environment #Pollution

Advanced NOx analysis.

Signal Group has announced the latest additions to its advanced Series IV gas analysers. The QUASAR instruments employ chemiluminescence detection for the continuous measurement of NOx, Nitric Oxide, Nitrogen Dioxide or Ammonia in applications such as engine emissions, combustion studies, process monitoring, CEMS and gas production.

Commenting on the launch, Signal MD James Clements said: “The sensing technology in these analysers is the result of several decades of development, delivering accurate, reliable analysers that are simple to operate. As part of the Series IV platform, they also offer market leading capability in communications and data management.”

Heated vacuum chemiluminescence is the reference method for monitoring NOx (combined NO and NO2), offering higher sensitivity with minimal quenching effects, and a heated reaction chamber facilitates the processing of hot, wet sample gases without condensation. Signal’s vacuum technology improves the signal to noise ratio, and a fast response time makes it ideal for real-time reporting applications. However, a non-vacuum version is available for trace NOx measurements such as RDE (Real-world Driving Emissions) on-board vehicle testing, for which a 24VDC version is available.

Series IV instruments are compatible with 3G, 4G, GPRS, Bluetooth, Wifi and satellite communications; each instrument has its own IP address and runs on Windows software. This provides users with simple, secure access to their analyzers at any time, from anywhere.

Internal logging and a colour touch-screen display provide users with simple onsite access to data, and a screenless version is available for systems integrators.

 @GasAnalysers #PAuto

Analyser for NOx detection.

As part of its comprehensive emissions monitoring analyser range, Servomex, the world leader in gas analysis, provides a key solution to cover the broadest range of emissions applications involving oxides of nitrogen.

The SERVOPRO NOx is a versatile analyser which uses the time-proven Chemiluminescence Detection (CLD) method to measure NO or NO/NO2/NOx concentrations, all in one package. The standard analyzer can be equipped with the Servomex Paramagnetic O2 sensor, and in addition there is a heated CLD version available for vehicle or engine certification testing.

The analyser is ideal for continuous emissions monitoring of industrial stationary sources, as well as ambient air monitoring. Using a photodiode equipped with a Peltier cooler to detect chemiluminescent light at speeds up to 5Hz, the NOx is a perfect solution for emissions testing in engines and vehicles.

Delivering an excellent linear range from trace levels to 1000s of ppmv concentrations, the NOx allows for user-selectable measurement ranges from 0-3ppm to 0-3,000ppm, all of which can be changed and recalibrated in the field, manually or remotely.

The standard version includes a Paramagnetic oxygen channel, internal zero/sample/span valves, and an internal sampling pump. A wet to dry conversion option is also available.

Barbara Marshik, Servomex’s Market Segment Manager - Power, said: “The SERVOPRO NOx is a must-have solution not only for any industrial stationary source but it is also an excellent choice for any mobile-source NOx emissions application. Using a high-sensitivity photodiode detector instead of a standard photomultiplier type ensures a long-lasting detector that requires no maintenance. With flexible ranges, ultra-low detection limits and a high dynamic range to meet any application requirements, the analyzer offers the highest level of performance for a low cost of ownership.”

The NOx joins the SERVOPRO SO2, which uses pulsed Ultraviolet (UV) Fluorescence technology, the SERVOPRO HFID which uses a heated-oven, Flame Ionization Detection-based detector for total hydrocarbons, methane and non-methane hydrocarbon detection, and the SERVOPRO 4900 multi-gas analyzer. These analyzers offer a comprehensive solution for monitoring NO, NO2, NOx, SO2, methane, total hydrocarbons, and non-methane hydrocarbons in stationary and mobile-source emissions applications that require the ultimate in low-level emissions monitoring.

@Servomex  #PAuto