Ecotech Serinus 30 - Repeatability Standard Deviation

TÜV Rheinland Energie und Umwelt GmbH
Luftreinhaltung
Report on the performance testing of the Serinus 30 ambient air quality moni-
toring system manufactured by Ecotech Pty Ltd measuring CO, Report no.:
936/21221977/D_EN
Page 79 of 253
EP_Ecotech_Serinus30_en.docx
7.1 8.4.5 Repeatability standard deviation
The repeatability standard deviation shall neither exceed 0.3 µmol/mol (i.e. 0.35
mg/m³) at zero nor shall it exceed 0.4 µmol/mol (i.e. 0.46 mg/m³) at span point.
7.2 Test procedure
After waiting the time equivalent of one independent reading, 20 individual measurements
both at zero concentration and at a test concentration (c
t
) similar to the 8-hour limit value
shall be performed.
From these measurements, the repeatability standard deviation (s
r
) at zero concentration
and at concentration c
t
(8-hour limit value) shall be calculated according to:
( )
1
2
−
−
=
∑
n
xx
s
i
r
where
r
s
is the repeatability standard deviation, in µmol/mol;
i
x
is the ith measurement, in µmol/mol;
x
is the average of the 20 measurements, in µmol/mol;
n
is the number of measurements, n = 20.
The repeatability standard deviation shall be calculated separately for both series of meas-
urements (zero gas and concentration c
t
).
s
r
shall comply with the performance criterion as specified above, both at zero and at the test
concentration c
t
(8-hour limit value).
The repeatability standard deviation at zero is used in combination with the slope of the cali-
bration function determined in 8.4.6 to calculate the detection limit of the analyser as:
B
s
l
zr,
det
3,3 ⋅=
where
det
l
is the detection limit of the analyser, in µmol/mol;
zr
s
,
is the repeatability standard deviation at zero, in µmol/mol;
B
is the slope of the calibration function determined according to Annex A using the
data from 8.4.6.
7.3 Testing
The test was performed in accordance with the requirements on testing as stipulated in
EN 14626. In accordance with these requirements, the test needs to be performed using the
component CO. DIN EN 14626 specifies that the test shall be performed at a concentration