What follows is a run-down of the key considerations that underpin the design of a true reference analyser. The EN standard reference method EN 14792 is intended for stack testing laboratories, to verify the installation of a continuous emissions monitor on an industrial chimney stack. In addition, it does not specify whether the NO2 component should be converted to NO prior to any water in the sample being condensed for removal. The standard does not specify whether the analyser should be heated or unheated, or whether the detector should be vacuum based or atmospheric. However, the method cites several alternative CLD configurations but it only stipulates chemiluminescence as the method of detection. The European Standard EN 14792 specifies chemiluminescence as the standard reference method (SRM) for the measurement of NOx in stationary source emissions. This is extremely important because the untimely discovery of any NOx measurement errors, interferences or excessive levels of uncertainty could prove costly. In addition, it will frequently be necessary for them to provide defensible measurement data in order to secure formal approvals in local markets. This is because stack testers simply require analysers that comply with certain performance requirements, whereas those in R&D require highly accurate, definitive measurements of NO, NO2 and NOx in order to fine-tune their designs and optimise the performance of their products. Organisations conducting combustion research have a different monitoring requirement to plant operators and stack testers. In many cases, this means that products have to be designed to comply with the local emission regulations, wherever they are sold. The designers of engines, boilers, turbines and incinerators seek to optimise combustion efficiency whilst minimising the harmful emissions of gases such as NOx. Globally, emission limits for NOx are becoming more stringent as governments seek to address these concerns. 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.”įrom 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 waters. It has been unclear whether these effects are caused by NO2 itself or by other pollutants emitted by the same sources (such as traffic). For example, in 2015, the UK’s Committee on the Medical Effects of Air Pollutants (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. Globally, a wide variety of organisations have published reports linking serious health effects with short- and long-term exposure to NO2. Examples include process boilers, gas turbines, stationary diesel engines, domestic boilers and wood burners. These include nitric oxide (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.Ĭonsequently, 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. NOx is a generic term for the oxides of nitrogen that have significant effects on the environment and human health.
NO2 is generated by industrial processes including cement manufacture. Instrumentation firm Signal Group takes a closer look at NOx measurement and the selection of an appropriate technology. 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. 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.