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The term NO x represents several forms of nitrogen oxides such as NO (nitric oxide), NO 2 (nitrogen dioxide) and N 2 O (nitrous oxide, also known as laughing gas).In a gasoline engine, NO is the most common form of NO x at around 93%, while NO 2 is around 5% and the rest is N 2 O.
Selective catalytic reduction (SCR) means converting nitrogen oxides, also referred to as NO x with the aid of a catalyst into diatomic nitrogen (N 2), and water (H 2 O). A reductant, typically anhydrous ammonia (NH 3), aqueous ammonia (NH 4 OH), or a urea (CO(NH 2) 2) solution, is added to a stream of flue or exhaust gas and is reacted onto a ...
A nondispersive infrared sensor (or NDIR sensor) is a simple spectroscopic sensor often used as a gas detector.It is non-dispersive in the fact that no dispersive element (e.g a prism or diffraction grating as is often present in other spectrometers) is used to separate out (like a monochromator) the broadband light into a narrow spectrum suitable for gas sensing.
NO y (or NOy) refers to the sum of NO x and all oxidized atmospheric odd-nitrogen species (e.g. the sum of NO x, HNO 3, HNO 2, etc.) NO z (or NOz) = NO y − NO x; Mixed Oxides of Nitrogen ("MON"): solutions of nitric oxide in dinitrogen tetroxide/nitrogen dioxide.
Most weld purging is carried out on joints made by the TIG or GTAW arc welding process. [6] When the laser welding process is chosen, joints or welds being made on reactive materials will need to be carried out and in the case of electron beam welding, this is carried out in a vacuum, in which case purging takes place by complete evacuation of all gas.
Infrared point sensors can be used to detect hydrocarbons [7] and other infrared active gases such as water vapor and carbon dioxide. IR sensors are commonly found in waste-water treatment facilities, refineries, gas turbines, chemical plants, and other facilities where flammable gases are present and the possibility of an explosion exists.
DEF from a separate tank is injected into the exhaust pipeline, and the exhaust heat decomposes it to ammonia. Within the SCR catalyst, the NO x are reduced by the ammonia into water and nitrogen, which are both nonpolluting. The water and nitrogen are then released into the atmosphere through the exhaust. [7]
In atmospheric chemistry, NO x is shorthand for nitric oxide (NO) and nitrogen dioxide (NO 2), the nitrogen oxides that are most relevant for air pollution. [ 1 ] [ 2 ] These gases contribute to the formation of smog and acid rain , as well as affecting tropospheric ozone .