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The levels of NO are around 100–2000 ppm (parts per million) and NO 2 20–200 ppm in a range of 1–10% O 2. The sensor has to be very sensitive to pick up these levels. The main challenges in the sensor development are selectivity, sensitivity, stability, reproducibility, response time, limit of detection, and cost.
Measurements allowed to see that at this road average traffic load of 1000 vehicles per hour, the reduction of nitrogen oxides in the air at ground level was 60%. [4] Some were skeptical about this discovery: in their opinion, it is necessary to reduce the level of harmful substances emissions, and not to eliminate their consequence - smog.
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 ...
Oxygen sensors are installed in the protected volumes to continuously monitor the oxygen concentration. The exact oxygen level to retain in the protected volumes is determined after a careful assessment of materials, configurations, and hazards. [3] Tables list ignition-limiting oxygen thresholds for some materials. Alternatively, the ignition ...
Among these are nitric oxide (NO), nitrous oxide (N 2 O), and nitrogen dioxide (NO 2), all of which are covered in the NAAQS. NO 2 is the oxide measured and used as the indicator for the entire NO x family as it is of the most concern due to its quick formation and contribution to the formation of harmful ground level ozone. [18]
Personal sensors can empower individuals and communities to better understand their exposure environments and risks from air pollution. [17] For example, a research group led by William Griswold at UCSD handed out portable air pollution sensors to 16 commuters, and found "urban valleys" where buildings trapped pollution. The group also found ...
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.
A NO x adsorber is designed to reduce oxides of nitrogen emitted in the exhaust gas of a lean burn internal combustion engine.Lean burn engines, particularly diesels, present a special challenge to emission control system designers because of the relatively high levels of O 2 (atmospheric oxygen) in the exhaust gas.