Calculation Sequence; Normalisation Equations - CODEL Energy Tech 401 Installation, Operation And Maintenance Manual

2.2.3

Calculation Sequence

2.2.4

Normalisation Equations

2.2.4.1 Correction to standard
pressure
2.2.4.2 Conversion to mass
concentration
Issue: A Revision: 1 Date: 24/07/19
The calculations for one complete operating cycle of the instrument are given
below :
measure D1 & D2

measure E1 & E2

compute Y

smooth Y

linearise and correct for path length

normalise measurement

smooth to produce final gas outputs

Normalisation of data collected by the analyser is essential to compare emission
levels of pollutants into the atmosphere. Software in CODEL's analysers performs
all calculations and provides results in various units, vpm, mg/m
derivation of these results is described in this section.
CODEL EnergyTech 401 gas analysers are cross-duct type and thus measure the
quantity (or number of molecules) of gas within their sight path.
measurement is converted into a concentration which is fully compensated for
the expansion effects of temperature, whilst assuming constant atmospheric
pressure. This basic measurement is referred to as 'ppm' (parts per million).
However, to obtain a true concentration 'vpm' (ppm by volume) the 'ppm' value
must be normalised for pressure using the following expression.
vpm =
where standard pressure is taken as 101 kPascals.
The next stage in the process is to determine the mass concentration. The
conversion at STP uses conversion factors determined as follows :
N =
where N =
RMM =
Ref: 100606
Section 2
General Description
3
ppm x standard pressure (abs)
measured pressure (abs)
RMM
V
conversion factor
relative molecular mass of the gas
3
and mg/Nm ;
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