Reliable solutions for measuring nitrogen oxides

Luke Purdie
Product Manager

The measurement of nitrogen oxides has become increasingly important for industries in order to comply with global and regional emissions regulations. As the global experts in gas analysis, Servomex delivers highly accurate measurements of nitrogen oxides (NOx) in a range of applications. The SERVOPRO 4900 Multigas continuous emissions monitoring system (CEMS) gas analyzer delivers part-per-million (ppm) measurements of nitric oxide (NO) and nitrous oxide (N2O) for regulatory compliance and clean air. The SERVOPRO NOx analyzer measures NO for industrial gas and vehicle emission applications, and for determining the nitrogen dioxide (NO2) and NOx content of a gas. The SERVOTOUGH SpectraExact 2500 photometric analyzer measures NO and N2O in a range of industrial processes, and is suitable for operation in hazardous areas.

Why measure nitrogen oxides?

Nitrogen oxides are one of the most significant contributors to air pollution. Nitric oxide (NO) and nitrogen oxide (NO2) – together referred to as NOx – are typically produced during combustion, and contribute to the formation of smog and acid rain, as well as affecting the ozone layer. For these reasons, NOx emissions must be monitored to ensure compliance with increasingly stringent environmental regulations.

How our analyzers work to measure nitrogen oxides for NOx analysis

Servomex’s analyzers rely on two key sensing technologies to support NOx analysis and nitrogen oxides measurement. Gas Filter Correlation (GFC) is an advanced Infrared sensing technology that uses the property of gases to absorb unique light wavelengths to detect the concentration of a selected gas in a mixture. For NO, it measures concentrations at ppm levels. It can also be used to measure nitrous oxide (N2O) and many other pollutants. Chemiluminescence sensing is a non-depleting, light-based technology that takes advantage of the light emitted by NO and NO2 in chemical reactions. It uses a photodiode to measure light intensity when NO reacts with ozone, calculating the NO concentration. It can also be used to infer the NO2 and total NOx concentrations in the gas.

NOx analysis solutions for emissions and compliance

The oxides of nitrogen are commonly formed as part of the combustion reaction, making this one of the key applications where a NOx monitor is required. The SERVOPRO 4900 Multigas provides a complete monitoring solution for CEMS gas analysis, combining up to three sensing technologies to deliver up to four simultaneous gas stream measurements. Combined with a suitable sampling system, it provides unparalleled MCERT (EN 15627-3) and QAL1 (EN14181) measurements of criterion pollutants and greenhouse gases. The SERVOPRO NOx analyzer is ideal for rapid-response applications such as vehicle and engine emissions certification testing, CEM, combustion efficiency, and process gas monitoring. It can be configured to meet a range of regulatory standards, including EPA 1065/1066 and LD Euro 6, and HD Euro V1. The SERVOTOUGH SpectraExact 2500 is designed to operate effectively in hazardous areas, with hardware compliance to SIL 2, IEC 61508, and ATEX, UKATEX, IEC Ex, and US Class 1 Division 2 variants available.

Our solutions for nitrogen oxides gas analysis

Servomex offers three key analyzer solutions for NOx emissions monitoring. The SERVOPRO 4900 Multigas uses Gas Filter Correlation sensing technology to measure nitric oxide and nitrous oxide in the ppm range, while the SERVOPRO NOx analyzer uses Chemiluminescence detector sensing for ppm NO measurements as well as NOx testing and NO2 analysis. The photometric SERVOTOUGH SpectraExact 2500 measures percentage or ppm NO and N2O in hazardous industrial conditions, using Gas Filter Correlation technology.

SERVOPRO 4900 Multigas

A comprehensive solution for analysis of multiple flue gas components

Luke Purdie
Product Manager

Specifically designed for Continuous Emissions Monitoring (CEMS) of flue gas, the SERVOPRO 4900 Multigas can deliver up to four simultaneous gas stream measurements.

It combines Servomex’s leading-edge sensing technologies with a modern digital platform, for next-generation performance at a low cost of ownership. For measurements that need to analyze and speciate NOx, NO and NO2, a NOx converter can be included.

A high-performance CEMS analyzer, the 4900 Multigas is backwards-compatible with existing 4900 installations and uses the same reliable measurement technology, providing trusted gas analysis combined with the advanced digital communications required by modern systems.


Combustion and ultra-low NOx emissions testing and monitoring in one simple analyzer

Keith Warren
Keith Warren
Process Oxygen, Zirconia & Oxygen Deficiency

The versatile SERVOPRO NOx gas analyzer uses the time-proven Chemiluminescence Detector (CLD) method to measure NO or NO/NO2/NOx concentrations all in one analyzer – perfect for continuous monitoring for industrial stationary sources emissions or ambient air, and fast enough for emissions testing in engines and vehicles.

The analyzer uses ozone (O3) which reacts with the nitric oxide (NO) in the sample stream, yielding an excited state of NO2 (NO2*) plus oxygen (O2). As the NO2* returns to a more stable state, it produces a chemiluminescent light of intensity proportional to the concentration of NO that was converted into NO2. A photodiode detector measures the light to determine a ppmv NO value.

To produce a total NOx signal, an internal converter turns any NO2 in the sample into NO. This stream is then subjected to O3 gas – the resultant reaction is directly proportional to the total NOx concentration. The analyzer calculates the final NO2 concentration from the NOx converter efficiency.


SERVOTOUGH SpectraExact 2500

Real-time photometric analysis of continually flammable sample gas streams

Chris Davis
Chris Davis
Product Manager

A highly flexible analytical solution adaptable to many applications, the SERVOTOUGH SpectraExact 2500 delivers proven performance and versatile operation in a resilient and reliable design.

It delivers a real-time online monitoring solution with accurate and stable analysis of a wide range of components, including percentage-level and parts-per-million-level nitric oxide. Field mounting capabilities enable flexible use in the harshest process conditions.

Robust and highly affordable, the SpectraExact 2500 uses an intelligent design and non-depleting sensing technologies to help to extend maintenance intervals and dramatically reduce ongoing costs.

Best-fit technologies for your nitrogen oxides gas analysis

Our nitrogen oxides analyzers deliver sensitive, ultra-low measurements of Ar for assay and impurity analysis, as well as process control.

Gas Filter Correlation sensors deliver stable, ultra-accurate gas analysis

An advanced form of Infrared sensing, Gas Filter Correlation (GFC) technology is ideal in applications with interferent background gases, delivering precise, sensitive measurements. It is used in our SERVOTOUGH SpectraExact 2500 photometric analyzer, and is a key technology for our SERVOPRO multi-gas analyzers, the MultiExact 4100, MultiExact 4200, and  4900 Multigas.

Learn more about Gas filter correlation technology

Non-depleting sensing technology for NOx analysis

Used in our SERVOPRO NOx gas analyzer,  Chemiluminescence  sensing is a light-based technology ideal for the measurement of nitric oxide (NO), nitrogen dioxide (NO2), and total oxides of nitrogen (NOx) in a wide range of combustion and emissions monitoring applications.



Learn more about Chemiluminescence technology

Nitrogen Oxides analysis resources

For more in-depth information about our Nitrogen Oxides analysis solutions, download our additional expert resources

Servomex Gas Guide issue 4

Servomex Gas Guide issue 4

ES Magazine Issue 27 Specifiers Guide

ES Magazine Issue 27 Specifiers Guide

ALL NEW SERVOTOUGH SpectraExact 2500F Product Brochure

ALL NEW SERVOTOUGH SpectraExact 2500F Product Brochure

SERVOPRO NOx Product brochure

SERVOPRO NOx Product brochure

SERVOPRO 4900 Multigas Product brochure

SERVOPRO 4900 Multigas Product brochure

Selected solutions for Nitrogen Oxides-based applications

Our digital Nitrogen Oxides sensors provide solutions to a wide range of processes that require an Ar analyzer.

Process heaters and furnaces

A choice of technologies to fit your application

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Servomex – gas analysis to empower a changing world

Servomex is the global leader in gas analysis, providing solutions for cleaner, more efficient industries, and enabling the manufacture of products that benefit everyone. With 70 years of expertise and research behind us, we deliver industry-changing gas analysis measurements for process control, quality, safety, emissions monitoring, and combustion efficiency.

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Global service support delivered locally

Wherever you are in the world, our network of service engineers provides the expertise you need to keep your argon analyzer operating at peak performance. With state-of-the-art service centers around the globe, you’ll always have the support your process needs.

Service team meeting customer

We provide tailored service packages that support your product throughout its life

Our global service network delivers the support you need to keep your analyzer or system operating at peak performance, for total peace of mind.

Broadly, we categorise our customers into two distinct groups

Purity & Specialty

Our Purity & Specialty (P&S) team provides products, knowledge and service to market sectors including industrial and medical gases, UHP gases, and semiconductor manufacture

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Industrial process & Emissions

Our Industrial Process & Emissions (IP&E) division is responsible for our gas analysis solutions in the power generation, hydrocarbon processing and emissions monitoring markets

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Choose the experts in Nitrogen Oxides gas analysis

The Servomex difference is clear from the start, all the way through to delivery of Nitrogen Oxides gas analysis system that will transform your process.

We consult with you to determine what you need

Our team stays in place throughout the project, ensuring consistent communication. This starts with identifying the parameters that the system must meet to ensure optimum performance and ease of use.

We design and build your system in our dedicated facility

Our schematics and documents are reviewed by the customer until the final design is agreed upon. Our skilled engineers then assemble the system at one of our cutting-edge regional centers, with continuous evaluation throughout the build process.

We test and deliver your integrated solution

After internal testing and an intensive Factory Acceptance Test (FAT), the finished system is shipped for installation. Our expert support team can commission and calibrate the system and provide any necessary operator training.

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