Continuous Emissions Monitoring Systems

With 25 years experience, we are the cems experts

continuous emissions monitoring systems (CEMS)

CEMS monitoring is required in a number of industries where air discharge is generated from combustion or a process throughout their business activities. Industries must have the right equipment to meet air quality monitoring standards. Parameters measured include CO, CO2, SO2,  NO, NO2, NOx, O2, NH3, HF, HCl, H2S, TRS, CH4, N2O, VOC’s, H2O, Opacity, Dust mg/m³, Mercury, Flow, Velocity and more.

industries include:

  • Gas & Coal Fired Power Plants
  • Rare Earth Processing Plants
  • Waste to Energy Plants
  • Manufacturing Plants
  • Petrochemical Refineries
  • Aluminium Smelters
  • Research Facilities
  • Paper Mills
  • SynGas
  • Steel Industry
  • Food Industry
  • Biosolids
  • Incinerators
  • Thermal Oxidisers
  • Sewage Treatment Plants
  • Boilers
  • Engine Emissions
  • Tunnels – Road, Rail and Mining – link to another landing page.
  • Stack Testers – Portable Emission Monitors and Manual Stack Sampling Equipment

iso accreditation

Our processes are managed under an integrated management system to: ISO 9001:2015 | ISO 45001 | ISO 14001:2015

what we can do for you:

Ensure you meet regulatory requirements and avoid heavy fines and/or legal action

Work with you to ensure minimal impact on plant operations for installation and maintenance

Reduce cost of ownership of equipment by supplying reliable, high quality equipment

Create a tailored solution for your application / technical specifications / installation site

Thomson Environmental Systems offer a wide variety of custom-made solutions to meet your site-specific Continuous Emissions Monitoring requirements.

We offer Insitu, Direct extractive and Dilution extraction systems, providing reliable, low maintenance systems to meet challenging applications such as TRS, VOC, HCL and NH₃ monitoring as well as value monitoring solutions for CO, NOx, SO₂ and more.

For reliable data and operation year after year, we integrate trusted, well-known brands such as Teledyne API, DURAG, Gasmet, Optical Scientific, Enotec, Auburn Systems, Tiger Optics and other quality components.

Systems are equipped with accessories for CEMS housing and calibration; including probe spiking, system alarms, probe blow-back and options for high temperatures up to 1200-1400C, O₂ & H₂O monitoring, data collection and reporting to Australian State, US EPA and European regulations.


Here's how we can help:

Systems Engineering and Integration

TES supply complete system solutions. Our team of engineers and instrument technicians are available to discuss your stack and process monitoring application, recommend equipment and design and engineer unique turnkey systems to meet your specific needs.
Our range includes unique technologies such as optical scintillation and FTIR, allowing us to measure effortlessly where measurement has not been possible before.

Turnkey Solutions

  • Insitu, Direct Extractive & Dilution Extraction Gas Analyser Systems
  • Insitu Dust/Opacity Analysers
  • Insitu Flow/Velocity Sensors
  • System Design & Integration
  • Sample Probes & Lines
  • Sample Clean Up Units
  • Calibration Equipment
  • Data Logging and Recording
  • Air-Conditioned Cabinets & Walk in Shelters.

Reliable + Durable, quality assured

TES supply low maintenance, high quality gas, flow/velocity and dust/opacity monitors for the toughest on-site conditions. All system components are thoroughly tested and system operation is verified and documented during Factory Acceptance Testing.

Testing and Wiring

All wiring, labelling and plumbing is performed by experienced professionals to meet or exceed your requirements.

Parameters Measured


Over 300 more
DustOpacityDust mg/m³Broken Bag Detection
Flow / VelocityUltrasonic, Optical Scintillation or Pitot
Industries ServedGas & Coal Fired Power PlantsManufacturing PlantsRefineries
Research FacilitiesPaper MillsWaste to Energy Plants
SynGasSteel IndustryFood Industry
BiosolidsIncineratorsThermal Oxidisers
Sewage Treatment PlantsBoilers 


types of Continuous Emissions Monitoring Systems

CEMS consist of numerous components that are capable of determining particulate, gas concentration and flow or the rate of emission of certain pollutants. Results are produced through analyses of measurement and also software.

CEMS are primarily classified according to the approach taken towards probe mounting: In-situ or extractive. With extractive systems, the analyser and probe are separated while the system removes and conditions the gas sample before it’s sent to the analyser in order to determine the contents. In-situ systems consist of mounting the analyser on the stack and the analyser then being in direct contact with the sample gas, which removes the need to condition the sample.

InSitu Gas CEMS

In-situ Gas CEMs sensors are installed directly into the stack, there is no sample drawn from the stack which means no conditioning, pumps or filters are required, saving costs and maximising the integrity of your results by reducing the loss of hydrocarbons from the sample conditioning process.

FPI’s Single Gas Analyser System Features:

  • No cross-interference
  • Fast response, less than 1 second
  • Diverse optical length (0.5-20m)
  • Install base of over 8000 instruments worldwide
  • International ATEX Certified.

FPI’s Single Gas Analyser (LGA) utilises Tunable Diode Laser Absorbtion Spectroscopy (TDLAS). The LGA System can accurately measure in harsh environments and is virtually maintenance free.

Direct Extractive & Dilution Extractive Continuous Gas Analyser Systems

We offer In-situ, Direct extractive and Dilution extraction systems, providing reliable, low maintenance systems to meet challenging applications such as TRS, VOC, HCL and NH3 monitoring as well as value monitoring solutions for criteria gases such as CO, O2, CO2, NOx, SO2 and more.

For reliable data and operation year after year, we integrate trusted well-known brands such as Teledyne API, M&C, Gasmet, Durag, and other quality components.

Systems are equipped with accessories for CEMS housing, data logging and reporting, calibration; including probe spiking, system alarms, probe blow back and options for high temperatures up to 1200-1400C, O2 & H2O monitoring, data collection and reporting to US EPA regulations.

  • Turnkey gas monitoring systems for process and emission monitoring
  • Custom design to suit your site requirements
  • Reputation for quality systems that hold up in harsh environments, including corrosive gases such as TRS & H2S Applications
  • Locally integrated and supported

Dilution Extraction Systems utilise an eductor-style dilution probe, non-heated sample line and Teledyne API or Tiger Optics Ambient analysers, proving accurate stack gas measurements while minimising maintenance in corrosive environments.

Dilution Extraction Gas CEMS draw less sample from the stack which means they are exceptionally low maintenance and ideal for monitoring corrosive gases in corrosive sample streams such as H2S and TRS.

Direct Extraction Systems can be mounted at ground level for ease of access for routine maintenance and the sample is analysed at stack concentrations, therefore analysers are of lower sensitive and require less frequent calibration.

Direct Extraction Systems offer a simple, economical option utilising heated probe, heated sample line, sample conditioning system, probe blow back (if required) and Teledyne API Medium and High Level analyser.

Gasmet FTIR analysers are also available for mutli-gas analysis.

Insitu Dust/Opacity Analysers

TES partner with various suppliers of reliable Dust and Opacity Monitors. Including:

Opacity Monitors

  • to meet US EPA PS 1 or TUV requirements

Laser Dust Monitor

  • Low maintenance, low calibration requirements, economical option
  • mg/m3 or Opacity output

Triboelectric Bag Leak and Dust Monitor

  • Bag leak detectors and solids flow monitors to monitor and measure dust, powders, and bulk solids for environmental and process control applications.

Insitu Flow/Velocity Sensors

TES offer Pitot Tube, Ultrasonic and Optical Flow Sensor technologies for Flow/Velocity Monitoring.

The Optical Flow Sensor (OFS) manufactured by OSI is a continuous flow measurement system for small and large stacks and ducts.

Advantages of Optical Scintillation flow measurement include:

  • Temperature, pressure and humidity have no impact on the measurement
  • Instrumentation is installed at a 90° angle to the gas flow, needing only one platform to access, rather than potentially two on smaller stacks
  • It is a true non-contact instrument – nothing protrudes into the stack. The instrument is very rugged, they are even installed in flare stacks! And normally there is no need for blowers unless it is a really dirty application.
  • Measurements are drift free
  • Measurement is across the entire stack (rather than one point when a pitot is used)
  • Path length and opacity do not affect the measurement
  • Compliant with US EPA 40CFR 60 and 75
  • Very low maintenance and ongoing cost of ownership (no consumables).

Several regulatory bodies around the world, across a host of different sectors require the reporting of environmental pollutant emissions which can be done through an emission monitoring system. CEMs continuous emission monitoring systems refer to the category of equipment utilised for this monitoring, generally required by or approved by these various aforementioned governing authorities. 

Gasmet CMM Continuous Mercury Monitoring System

Mercury can be a challenging component to measure for many technologies and systems as it exists in various forms, including elemental mercury and mercury compounds, as well as mercury that is bound to dust particles. An integrated thermal converter converts all mercury compounds to elemental mercury to measure total gaseous mercury.

Thanks to the CVAF (Cold Vapor Atomic Fluorescence ) technology, which offers the highest sensitivity in the world (detection limit of 0.02 μg/m3), a fairly high dilution ratio can be used. An internal nitrogen gas generator dilutes the sample in a 1:50 ratio – since there is a lower amount of sticky mercury compounds, the Gasmet CMM delivers faster, reliable and extremely accurate results, without interferences from other gases.

The system is fully automatic, with Hg0 calibrations conducted at user-defined intervals.


  • With the lowest Certified measurement range in the world, 0-5 µg/m3 means your Mercury monitoring system is ready for stricter emission limits in future.

  • Automatic QAL 3 validation tool for Hgo and HgCL2 paired with simple, low cost maintenance, means less down time and more room to breathe with your data capture rate.

  • Being a continuous monitoring system, you will gain insight on the variability of mercury emissions over time and between differing feedstocks.

Standards Met

EN 15267, TUV certified & MCERT Certified


Measuring Mercury (Hg) continuously from hot, wet and corrosive gas streams of industrial processes. Continuous Mercury monitoring is generally of interest for:

  • Incineration processes,
  • Power Plants,
  • WtE Plants,
  • Cement Kilns
  • Rare Earth
  • Soil Remediation Facilities

As a Dilution Extraction System, it can be installed at ground level for ease of access and maintenance.



iso accreditation

Our processes are managed under an integrated management system to: ISO 9001:2015 | ISO 45001 | ISO 14001:2015

CEMS Equipment
Frequently Asked Questions

Will my CEM be supported here in Australia?

All Equipment supplied by TES in Australia and New Zealand is supported by TES. We have factory trained technicians located strategically around the region and stocked spare parts. TES can assist with client CEM Design, supply, installation, commissioning and on going maintenance.


Do I need a data reporting system?

TES can supply you wish a standalone data acquisition and reporting system to compliment your CEM or you can specific the outputs required from the CEM to allow you to take the data directly into your existing plant system. Talk to us today about your specific needs.

How do I minimise the downtime and maintenance of my CEM?

It is critical that the right technology and equipment is selected for your specific stack parameters. TES offer many different technologies and can match the technology and design your CEM to meet your specific situation, ensuring maximum uptime of your instrumentation and minimal maintenance.

What Different Types Of Monitoring Are Used To Measure Emissions?

Monitoring generally refers to the ongoing process of collecting and using measurement information or other data to evaluate performance against a status or standard. When it comes to regulatory requirements relating to air quality, monitoring consists of ambient and stationary source monitoring.

Ambient monitoring refers to the collection and measurement of ambient air samples to assess the air pollutants within the atmosphere in comparison to standards of clean air. Stationary source monitoring is in reference to the collection and use of measurement data at stationary emission sources, such as manufacturing plants and facilities. This is to evaluate the level of air pollutants being emitted from processes/work practices and assessing the performance of control devices for emissions in that particular environment.

How Does CEMS Monitoring Function & Why Do We Need It?

The components of a continuous emissions monitoring system may include, emission analysers, sample lines, sample probes, sample conditioners, calibration gases, analyser shelters, reporting software and more. A total CEMS is, in practice, typically purchased via an integrator for systems, responsible for designing and assembling the system based on requirements. Since they’re customised, the combination of options for CEMS are virtually limitless.

Every continuous emission monitoring system is built in compliance with certain regulations that are known as performance specifications or methods. While clients may not always make the conscious choice to install an emissions monitoring system themselves, CEMS are often required to comply with these regulations and any additional requirements that may be deemed necessary.

While there are numerous types of continuous emission monitoring systems, the most common process is when the non-diluted component of exhaust gas has been extracted from a stack via a gas sample and sent through conditioning systems before analysis by the emissions analyser.

The purpose of air quality regulations are to try and reduce the types and amount of air pollutants released into the environment. The measurement of these air pollutants is something that many people may not be familiar with. There are different ways to approach this, including point in time sampling and extrapolated figures on a long-term basis. The other approach is continuous emissions monitoring as an ongoing process.

Which Pollutants Are Monitored?

Usually monitored pollutants can include both toxic pollutants or criteria pollutants. Some of the pollutants that are examined include carbon monoxide, carbon dioxide, , nitrogen dioxide, nitric oxide, sulfur dioxide, Hydrogen Sulfide, Total Reduced Sulfure, VOC’sand particulate matter.

Toxic air pollutants are hazardous and classified as a cause of major health problems. Air quality regulations and programs specify which pollutants are regarded as toxic and dangerous.

Monitoring data is essential in assessing air quality trends and assessing the effect of pollution generated in the environment. Monitoring aims to evaluate the atmospheric status and provide information about air quality to the public, industry, scientists and regulators. CEMS allow  operating facilities to provide data to regulatory bodies to prove they are meeting their operating licence requirements and not exceeding emission limits. CEMS can also be beneficial to process operation efficiency.

Components Of Continuous Emission Monitoring Systems

Continuous Emission monitoring is often required due to regulations set by authorities/governing bodies to ensure continual compliance with standards. The rules are specific and relate to using reference methods aimed at substantiating the precision and accuracy of a continuous emission monitoring system. This consists of probe or sensor hardware, mounting, sample conditioning, enclosures/shelters, analysers, workstations and data acquisition. Feel free to get in touch with our team for more information.

let's find your
CEMS monitoring solution

If your equipment doesn’t do its job properly, you can’t do yours. Let’s find you a reliable, high quality solution to meet your requirements and make your life easier.

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With offices across Australia in NSW, QLD, ACT, VIC and WA we have a local office nearby waiting to help. For our customers in Africa we have an office in Ghana. If you’re in New Zealand or elsewhere overseas, we have dedicated team member ready to help with whatever you need.

Whether you have a license requirement, specification needs or external considerations, our team of experts can  guide you to the right solution.