M&C TechGroup PMA 100 Operator's manual - Manual (Page 27)

9-3.12-ME M&C Products Analysentechnik GmbH
- 27 -
13.Calibration
13.1 Calibration
Four calibration modes are available with the analyser PMA100:
• manual calibration,
• manual calibration offset,
• autocalibration offset, and
• autocalibration.
The calibration gases are given to the ‘sample in’ connec-
tion, located on the back panel of the PMA100 (see 8.1, fig. 7).
In case of autocalibration two respectively three valves are
controlled by the analyser menu. The connection of the cali-
bration valves is described in chapter 8.2.
A detailed description of the menu-driven handling is given
in chapter 12.
Faults during the calibration procedure are displayed in the
main menu like:
E ... O
2
-calibration.
The fault message is also stored in the calibration log-book
with an
E ... followed by the shortcut for the calibration
mode, the date, and the time the calibration is carried out.
If the zero and the span gas concentration deviates more
than 5Vol.-% to the adjusted concentration, a calibration
cannot be carried out. The deviation is displayed as an
error message.
In case of autocalibration flow through the analyser is
necessary. Otherwise an error message is displayed and
the calibration cannot be carried out. The offset calibration
is a single-point calibration and can be carried out, e. g.
with ambient air only.
The calibration modell depends on the fact that in spite of a
drift the zero point remains nearly to zero, and the calibra-
tion of the span gives a proper accuracy.
It is recommended to use a span gas concentration very
close to the required measuring range.
13.2 Cross-sensitivity
The paramagnetic measuring principle is based on the very
high magnetic susceptibility of oxygen. In comparison to
oxygen, other gases have such a minor susceptibility, most
of them are not even worth mentioning. Exception to this
are the nitrogen oxides. However, as this gas is in most
cases present in a very low concentration, the error is still
negligible.
The next table shows a list of cross-sensitivities. All values
based on a zero calibration with 100 Vol.-% N
2
and a span
calibration with 100 Vol.-% O
2
. The cross-sensitivities in the
table are valid for 100 Vol.-% of the corresponding gas.