ZIROX SGM7.2, Руководство пользователя

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Oxygen Monitor SGM7.2 8 Operation
8.3 Calibration
Especially before measurements with high accuracy requirements a
calibration should be made (The stability of the measuring cell is so high
that a check-up is necessary once a year only!).
The device must be at working state
for more than 1 hour before
calibration!
8.3.1 Zero Gas Calibration
The check-up is very important if measurements have to be made near
20 Vol.-% oxygen. Because of agings and small mechanical instabilities
the heating can be changed. Due to this changing the cell voltage will be
also changed. This misvoltage will be compensated by zero point
calibration. For the zero point calibration surrounding air must flow
through the device by later measuring gas velocity. This state will be
realised by internal pump or external pump (e.g. aquarium pump).
First “Calibration” and than “Calibration ZERO POINT” will be selected
via keyboard. After selecting “CALIBR. ZERO:” the calibration will be
started by “ENTER”. After approx. 5 s the calibration is finished. The
calibration will be leaved by „RETURN“ and „ENTER“. The calibration
will be saved by quit with „YES“.
8.3.2 Span Gas Calibration
For this the SGM7.2 must be flowed through by certified span gas
(oxygen concentration near later measuring conditions).
First “Calibration” and than “CALIBR. SPAN GAS” will be selected via
keyboard. The span gas oxygen concentration must be set. After
selecting “CALIBR. SPAN:” the calibration will be started by “ENTER”.
The stability of the measuring value will be checked during the
calibration. The real calibration process will be start as recently as the
signal produced by span gas is stable. Therefore the calibration process
can taken long variably (variation smaller than 1 % in 4 seconds).
If the stability is not given the calibration will be stopped after 60
seconds.
Furthermore the deviation of measuring value from setpoint will be
evaluated. At zero point calib/- 20 mV (cell voltage), at span gas
calib/- 20 % of measuring value (cell voltage) are allowed.
For the correction following equation applies: Uc
ell
(korr)=(Uc
ell
+A)*B
U
zell
= measured cell voltage
A = cell voltage at zero point
B = Factor for final value correction
The calibration will be leaved by „RETURN“ and „ENTER“. The
calibration will be saved by quit with „YES“.
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