Test & measurement


NOx measurement in combustion products and processes


NOx gases are mostly produced by the combustion of hydrocarbons 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. Here, the experts at Signal Group describe the need for monitoring NOx and explain the factors behind the choice of technology


human health. These include nitric oxide N


(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 repor ts linking serious health effects


with shor t- and long-term exposure to NO2. For example, in 2015, the UK’s Committee on the Medical Effects of Air Pollutants


52 February 2021 Instrumentation Monthly


Ox is a generic term for the oxides of nitrogen that have significant effects on the environment and


(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


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