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NDIR500 CO & CO2 analyzer

Conventional analyzers

The Non-Dispersive Infra Red (NDIR) measurement technique  is the industry-standard method of measuring engine exhaust carbon monoxide (CO) and carbon dioxide (CO2). Conventional NDIRs have response times of 1-2 seconds, and are typically used to measure "bag emissions" where the concentration changes very slowly.

A need for fast emissions analyzers

During the 1-2 seconds it takes a conventional NDIR to respond, an engine will undergo many firing cycles. The conditions inside the combustion chamber can vary significantly between successive firing cycles- particularly when the engine conditions are changing rapidly such as during engine start or speed/load transients. The Cambustion NDIR500 has a time response as low as 8ms T10-90%. This allows the NDIR500 to distinguish between two adjacent firing cycles, and even offer information about the variation in CO and CO2 concentration during a single exhaust stroke.

Benefits of fast emissions analyzers

NDIR500 sample headAccurate measurement of exhaust emissions brings valuable insights into engine operation, and assists calibration engineers in reducing the engine out emissions. This can assist in emissions compliance while reducing after-treatment costs.

The brochure may be downloaded here.


The NDIR500 is frequently used to calibrate and develop Exhaust Gas Recirculation (EGR) systems for NOx control. Through measurement of the CO2 concentrations in the exhaust, and at various points through the EGR system, the system behavior can be measured and models verified.

The NDIR500 can make measurements of the CO2 concentration in pre-combustion gas sampled from the cylinder. This allows the total residual gas fraction to be measured (i.e. internal and external EGR) and is particularly useful in revealing features such as poor EGR distribution on multi-cylinder engines, or the effects of variable valve timing on trapped residuals.

During cold start of a spark ignition engine, significant fuel puddling can occur in both port- and direct-injection engine types. This fuel is not available for combustion at the spark, and subsequently exits the cylinder through the exhaust valve. The situation may arise where combustion is lean (low availability of vaporized fuel at spark) but the engine out hydrocarbon concentration is very high.

This high HC concentration can cause sensors such as UEGOs to incorrectly indicate the AFR. By simultaneously measuring the CO & CO2 concentration in the burnt gas, the NDIR500 can be used to calculate the AFR (or lambda) for the gas which took part in combustion. This calculation can be performed for each firing cycle during and after engine start. Such data is particularly useful when looking at GDI engine start (where the time available for vaporization is less) or when using alternative fuels such as ethanol, which vaporizes less readily.

The NDIR500 is available with support for AK protocol, allowing easy integration with the test bench for improved test reliability and reduced workload.

To read more on fast gas analyzer applications such as residuals measurement, AFR calculation etc please visit our page on Spark Ignition Engines.

See Applications and sample data for more information on these and other applications.

Download a brochure.

Contact Cambustion for more information and prices.


Dr. Radut Consulting