Ecotech Serinus 44 - Background;Theory; Measurement Theory; Figure 1 - Simple Pneumatic Diagram; Equation 1 - Chemiluminescence Reaction for no

Introduction
Page 21
1.4 Background/Theory
Oxides of Nitrogen (NO
X
) are the product of endothermic reactions within combustion engines and
cause significant environmental pollution.
The main source of NO
X
emissions is from hydrocarbon combustion such as automobile engines or
the burning of coal for power production. These pollutants are harmful to humans and create ozone
gas (O
3
) and acid rain. NO
X
is a major component of the smog found in industrial cities and is harmful
to people with respiratory diseases such as asthma.
Ammonia (NH
3
) is mainly generated from agricultural sources, with hot-spots found particularly near
intensive pig and poultry farms. Ammonia pollution causes both acidification of soils and a decrease
in the richness of plant species.
1.4.1 Measurement Theory
The measurement of the NO/NO
2
/NO
X
/NH
3
/N
X
is performed using the gas phase chemiluminescence
method:
Figure 1 – Simple Pneumatic Diagram
 Sample air is drawn into the reaction cell via three separate (alternating) paths; the NO, NO
X
and
N
X
paths.
 The first path is drawn directly to the reaction cell. NO gas present in the sample reacts with
ozone according to the following reaction.
NO + O
3
 NO
2
* + O
2
Equation 1 – Chemiluminescence Reaction for NO