Environmental monitoring is used to describe the various processes, tests and investigations that are carried out in order to monitor the state of the environment and its changes, to understand and protect it. One of the major monitoring areas is air quality monitoring, which requires highly accurate measuring instruments. Heraeus Noblelight’s new light solution is developed for high accuracy, fast and real-time NOx measurement, together with very low operating costs.
The Heraeus plug & play light solution
NOx instrument development based on UV Resonance Absorption Spectroscopy (UV-RAS) has been difficult in the past, due to challenges in tuning the UV-lamp operation within its environment to optimize lifetime and intensity.
The NOx electrodeless discharge lamp (EDL) is a lamp with N2, O2 gas fill that emits a spectrum in the wavelength range between 200 nm to 800 nm. NOx-specific spectral lines in the 200 nm region can be used for the detection of NO and NO2, H2S, NH3, SO2 and other pollution gases.
Heraeus Noblelight’s new plug & play light solution for reliable NOx measurement is a lamp module that offers a pre-tuned UV-light source in a stable environment to ensure optimized performance. The NOx lamp module has an integrated EDL and comes with the corresponding power supply combined in a box. This makes integration into an OEM UV-RAS system very easy and cost efficient, plus light source replacement at End Of Life is by simply replacing the module in the field.
Fast and very accurate
High accuracy and stability are required in any measurement process. The new NOx module delivers both and even more. It is easy and effective in use, and without the need for consumables, it ensures very low operating costs. Enabling fast and accurate absorption measurements without cross-interference from water and CO2 , it saves time during the measurement process and makes dynamic (real time) measurements possible with high measurement confidence - a real competitive advantage for UV-RAS compared to other technologies.
Different methods to measure NOx
NOx is a generic term for the nitrogen oxides NO and NO2. It reacts in our atmosphere to form a wide variety of toxic products, as well as supporting the formation of ground-level (tropospheric) ozone.
Sources of NOx are predominantly man-made: burning fossil fuels for energy generation, such as coal-,oil- and gas-fired power stations, refuse incineration, some chemical processes and vehicle fuels, like modern diesel cars, used for land, water and air transportation.
Common methods for measuring NOx include sensor technologies based on chemiluminescence and electrochemical techniques.
This requires conversion of NO2 to NO for measurement or calculation of the NO2 content based on an assumed NO:NO2 ratio. In addition, NOx can be measured with infrared radiation, which can be affected by the content of H2O and CO2 in the sample. Direct UV absorption measurement
of both NO and NO2 is the more precise way to measure total NOx for continuous emissions monitoring, and measurement in the UV-region avoids the influence of H2O and CO2.
