TÜV Rheinland Energie und Umwelt GmbH
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Report on the performance testing of the Serinus 30 ambient air quality
monitoring system manufactured by Ecotech Pty Ltd measuring CO, Report
EP_Ecotech_Serinus30_en.docx
7.1 8.4.6 Lack of fit of linearity of the calibration function
The lack of fit of the calibration function shall not exceed 0.5 µmol/mol (i.e. 0.58
mg/m³) at zero point and 4 % of the measured value at concentrations above zero.
7.2 Test procedure
The lack of fit of linearity of the calibration function of the analyser shall be tested over the
range of 0 % to 95 % of the maximum of the certification range of CO, using at least six con-
centrations (including the zero point). The analyser shall be adjusted at a concentration of
about 90 % of the maximum of the certification range. At each concentration (including zero)
at least five individual measurements shall be performed.
The concentrations shall be applied in the following sequence: 80 %, 40 %, 0 %, 60 %, 20 %
and 95 %. After each change in concentration, at least four response times shall be taken in-
to account before the next measurement is performed.
Calculation of the linear regression function and residuals shall be performed according to
Annex A of DIN EN 14626. All the (relative) residuals from the linear regression function shall
fulfil the criteria as stated above.
Establishing the regression line:
A regression line in the form of
is established through calculation of the func-
tion
To calculate the regression, all measuring points (including zero) are taken into account. The
total number of measuring points n is equal to the number of concentration levels (at least six
including zero) multiplied by the number of repetitions (at least five) at each concentration
level.
The coefficient a is obtained from
where
a is the average of the Y-values;
Y
i
is the individual Y-value;
n is the number of calibration points
The coefficient B is obtained from
( )
2
)(/)(
zizii
XXXXYB −−=
∑∑
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