Environnement AF22e, Technical Manual, Page: 80 / 118

Environnement
S.A
AF22e
Duplication prohibited
APRIL 2016
3–46
−
Connect analyzer sample inlet to manifold dilution system.
−
Adjust the dilution system in order to generate a total zero air flow higher than the analyzer sample
flow rate by 20%.
−
Generate zero air. Wait for measurement to stabilize (recommended duration: 600 sec). Note Z
SO
2
value, as a percentage of selected full scale, named ECH.
−
Follow steps in section 3.5.3.2. (« span point correction » section) to adjust calibration coefficient.
ECH is used to name the analyzer full scale.
−
SO
2
measurement : use formula below to calculate generated span value:
=
×
(1)
Where:
is SO
2
concentration of generated gas at manifold outlet,
is SO
2
concentration of certified cylinder,
is SO
2
flow in NI/min,
is dilution air flow in NI/min.
To calculate read value (in ppb) to be taken into account, use following formula:
= ×
(2)
Where:
is the recorder value, in percentage of recorder full scale,
is the analyzer full scale,
was measured previously.
−
Then generate five SO
2
concentrations within 15 and 90 % of the full scale. For that, vary
and/or flows.
−
Plot read values as a function of values, including zero air point. Check linearity.
−
Plot, or calculate using the least squares formula, the calibration line of the analyzer.
= × +
(3)
Where:
: is the linear regression coefficient (slope), and is calculated as follows:
=
× ∑ × ∑ × ∑
× ∑ ∑
(4)
: is the constant linear regression term (intercept), it is calculated as follows:
=
∑
× ∑
(5)
: is the data number.