A Comprehensive Guide to CEMS Gas Analyzers

Check this guide on implementing Continuous Emission Monitoring Systems (CEMS) with additional details on CEMS gas analyzers.  Here, we go over technical specifications, calibration procedures, and other details for data acquisition.  

You probably need to follow CEMS requirements and regulations.  Examinations for analyzers include interference tests and temperature drift tests.  Improve your understanding of industrial emissions tracking and improve your operations with respect to accuracy, reliability and compliance.

This text is a summary of the instructions provided in the Alberta CEMS Code, sections 2 to 4.

Section 2.0 - Overview of monitoring plans

You're setting up a system to monitor pollution from an industrial operation. Here's what you need to do:

- Describe how you're going to design, install, operate, and maintain your monitoring equipment.

- Send this plan to the Director at least 90 days before you start using the monitoring equipment.

If you want, you can do it earlier.

Existing vs. new:

- If there's no pollution monitoring system yet, you need to design and plan a new one.

- You might not need a new plan if you're upgrading or re-certifying an existing system.

Ask the Director first if you want to do anything different from the pollution monitoring rules before you make this plan.

Monitoring and controlling industrial pollutionDesign, Quality Assurance, Data Reliability for Pollution Monitoring

Details: Your plan needs to be detailed. Here's what you need:

- What does your industrial operation do, how does it control emissions, and when will it start operating?

- Draw a picture of where your pollution comes from and where you're putting your monitoring equipment.

- If there are any obstacles or oddities, mention them.

- Describe how your monitoring equipment works, what it measures, and how it collects and stores data.

- Tell the authorities how your machines run and what pollution controls you have.

Timeline for developing the Quality Assurance and Quality Control Program (QAP):

- This is how you'll make sure your data is reliable.

- Test and certify your monitoring system: Share your plan.

- Explain what data you'll report, how often, and how.

- Electronic Submission: Once you're done, send this plan to the Director electronically.

- If the Director wants more details, be prepared to add them.

This can be compared to making a super-detailed blueprint for pollution tracking. You need to describe how it will work, where it will be, and how you'll make sure it's accurate. Don't forget to follow the rules spelled out in the Code!

Section 3.0 - Design and test optimization of CEMS gas analyzers

3.0 to 3.1 - In these parts, we'll talk about the technical specs and requirements for gas analyzers used in CEMS. Industrial pollution can be measured and controlled using your CEMS.

Here's what you need to know:

CEMS sets minimum design specs for different types of analyzers to ensure accurate readings, no matter the manufacturers.

These are the minimum design specifications for new gas analyzers installed since January 2022.

Certain CEMS gas analyzers require flowing test gas for calibration (CGA), which helps ensure accuracy. CGAs must be possible on analyzers purchased after this Code has gone into effect.

Table 1 lists the minimum design specifications for gases like sulfur dioxide, nitrogen oxides, and carbon monoxide. Detection limits, interference rejection, and temperature responsiveness are all part of these specs.

Analyzers need to have a wide operating range. All expected concentrations of the gas need to be covered. As a result, accurate measurements are made and possible emission limit violations can be monitored.

For accurate measurements, the majority of readings must fall within 20% to 80% of the analyzer's full scale. Readings outside this range can't be used for calculations, but still need to be reported.

When emissions can vary a lot, dual-range analyzers are a good option. This section outlines what gas analyzers in CEMS must do to ensure accurate and reliable monitoring of industrial emissions.

Gas analyzer testingAnalyzing and testing

3.2 to 3.4 - The purpose of this section is to discuss the technical requirements for data acquisition and handling in CEMS. CEMS measure and report industrial emissions. Here's how it works:

Data Acquisition and Handling (DAS): The DAS controls CEMS functions, collects data from analyzers, stores data, and makes calculations. For accurate and reliable emissions data, it's crucial.

Validity and resolution of data:
DAS data is used to calculate hourly averages and must be retained for validation.

It's considered quality assured if the data falls within the calibrated operating range.

The data outside the calibrated range must be reported, but it's not considered quality assured.

Gas concentrations, temperatures, and flow must be calculated and stored every hour. Every one-hour average must have at least 75% of the possible one-minute base averages.

Adjustments can be made if the CEMS gas analyzer's scan rate is faster than 1 minute.

Calculate and report data for partial hours when the source runs for less than an hour.

Availability of CEMS:

- Continuous emissions data is provided whenever the source is running with CEMS.

- In a calendar month, percent availability is calculated by dividing analyzer operation time by source operation time.

- During source operation, effluent is discharged during startup, shutdown, and other processes.

- Analyzer operation time includes routine and pre-planned QA/QC activities.

- Each CEMS gas analyzer must report percent availability and meet performance specs.

- It still calculates percent availability if an analyzer goes down while the source is still up.

- Valid hours represent quality-assured, reportable data, not simply the percentage of availability.

Back-up data sources:

When the primary data source is down, you can use a temporary backup. In order to use a backup source, it must produce the same data as the primary source.

Back-up data must be outlined in the QAP (Quality Assurance Plan).

Back-up data must be flagged in the CEMS User Manual.

This section explains how CEMS collects, validates, and reports data. In order to ensure continuous and reliable emissions monitoring, it emphasizes maintaining data quality, calculating percent availability, and using backup data sources.

3.5 - Test for interfering analyzers

Since 2022, you have to make sure your new gas analyzer can accurately measure gases without getting messed up by other gases.

This can be done by getting a certificate from the manufacturer saying the analyzer they tested met the standards, or by testing it yourself:

- Get the analyzer warmed up.

- Use low- and high-range test gases to calibrate it.

- Set up test gases that contain one interfering gas each.

- See how much these interfering gases mess up the measurements.

- Check Table 1 to make sure the total interference isn't too high.

You can do this test before or after installing the analyzer.

Temperature-responsive zero and span drift tests (3.0.1):  Installing a new CEMS gas analyzer after January 2022 means making sure it can handle temperature changes.

- You can get a certificate from the manufacturer or do your own test:

- The analyzer should be in a chamber where you can control the temperature (between 5°C and 35°C).

- Warm it up.

- Use the right gases to calibrate it at 25°C.

- Let it stabilize.

- Use different temperatures for test gases.

- Take notes on how the analyzer responds.

- Calculate how much the temperature changes the readings.

- Make sure these changes are within the limits shown in Table 1.

Don't turn off the analyzer while you do this temperature test.

It's important to do these tests to make sure the CEMS gas analyzer works and gives accurate readings despite interfering gases or changing temperatures.

Section 4.0 - Specifications and tests for CEMS installations

4.0 to 4.1 - Specifications and test procedures:

In this section, we talk about how to install equipment that measures smokestacks and chimneys.

- Installers must follow these rules:

- If they make major changes to the stack or chimney, they have to follow these rules from January 1, 2022.

- The term "new installation" refers to adding new parts or installing equipment that wasn't there before.

- Make sure they follow the manufacturer's instructions.

Technical Specifications and Protocols for AnalyzersCEMS and gas analyzer regulations

It's important where this equipment goes:

People shouldn't risk their safety during hazards like thunderstorms or heavy snow, but it should be easy to access in normal weather.

Equipment should be able to handle the weather where it's placed. For example, it has to work in temperatures between -40°C and +40°C at a power plant. Maybe you will need to put it in a shelter.

Gas analyzers, flow analyzers, and temperature sensors have to go in specific places:

- Following the Alberta Stack Sampling Code or EPA guidelines.

- A minimum of two times the diameter of the stack, duct, or chimney downstream of important places like control devices.

- Upstream from where the smoke comes out, at least half the diameter.

- Except for some flow analyzers, a certain distance away from reference method ports.

- Point or path-type measuring equipment has to be placed at least one meter away from the stack or chimney wall, or right in the middle of the smokestack.

4.2 to 4.5 - Ports for injecting test gas:
It depends on how the CEMS (Continuous Emission Monitoring System) works where they put test gas injection ports.

CEMS in-situ:
- They have to flood the analyzer with test gas if it's a point-type CEMS.

- You need to introduce test gas at a point to check the optical and electronic parts of a path-type CEMS.

Extractive CEMS:
- The test gas should be introduced at the probe or as close to the stack exit as possible if they're measuring gas concentration directly.

- It should go in before dilution, at the probe, or close to the stack exit if it's a dilution system (in-stack or external).

- The sample they get from the stack, duct, or flue must be a good representation of what's actually coming out.

- In a flow, gases mix well most of the time, but sometimes they don't. It can happen when different gas streams meet, or when the gases have different temperatures, or if the flow slows down, or if the stack changes shape.

- The flow can even create a swirling pattern, making it hard to find a good spot.

- You need to put the sampling probe or analyzer where gases mix well and avoid putting it where it might interfere with other parts of the system.

Test for stratification:
Make sure the gases mix well at the sampling spot to make sure they're sampling emissions correctly.

As of early 2022, new CEMS installations must test how gases flow in the stack or duct before or during certification.  Before or during certification, test if gases are mixed well in the stack or duct for each type of gas they're measuring.

There might need to be a retest if the gases flow differently or if the equipment isn't working right.  Test results must be reported, kept on file at the industrial operation, and made available for inspection.

Elevating Your CEMS Audits with Calvin Consulting Group Ltd.

Calvin Consulting Group Ltd. pioneers Continuous Emissions Monitoring System (CEMS) Audits to ensure compliance with Alberta's stringent regulations.  CEMS Quality Assurance Plan (QAP) and Alberta CEMS Code are audited annually by Alberta Environment and Protected Areas (AEPA).

What makes Calvin Consulting different?  

- Over two decades of experience with CEMS Audits.

- Knowledge of Alberta CEMS Code and QAP standards.

- Supporting clients with corrective action plans and training.

Let Calvin Consulting Group Ltd. handle your CEMS Audit.  Get in touch with us at

Contact Barry at CCGL for your CEMS audit.

We make compliance easy.  After stack testing is handled by other firms, we analyze and interpret the data to help you make needed submissions and subsequent decisions.

Clean air is our Passion...Regulatory Compliance is our Business.

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Make sure your emissions monitoring is accurate and reliable by using prescribed calibration methods, and data acquisition techniques.  This guide walks you through CEMS requirements while emphasizing adherence to regulations and quality control.

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