7
(See also Operating Instructions for
MD8 airscan Air Sampler)
A complete reference curve for
the flow rate sensor is stored in the
MD8 airscan software, which can be
brought into line with each instru-
ment by the 3-point calibration.
In the 3-point mode, the air flow
rates at the 3, 5 and 7 m
3
/h settings
are successively run and compared
with the values measured by the
calibration unit 16756.
Calibration can be interrupted at
any time by pressing Stop. When
the unit becomes overheated, cali-
bration is interrupted automatically.
The points measured and recorded
up to this interruption will be
remain stored and the unchanged
points are also stored.
You can call up the calibration
menu when the MD8 airscan is in
the initial starting position, i.e.
the message “Sartorius MD8 ready
to start” is displayed, by simultane-
ously pressing the
and
keys
for 3 seconds.
The calibration function is shown in
the display by the message:
“– Calibration – 3 point (Start)”.
When Start is pressed with the unit
in this position, the 3-point calibra-
tion mode is started.
6.1 Calibration Procedure
(After connection of the calibration
unit is completed as described in
Section 5).
a) The MD8 airscan moves to the first
measurement point, and continual-
ly displays the nominal and actual
values
(The message in the display reads:
“Nominal 3.0 m
3
/h Actual:
xx m
3
/h”).
b) As soon as the nominal value is
reached and stabilized, which can
be recognized from the actual value
display, press the parameter key
.
c) The MD8 airscan now continues to
run uncontrolled, i.e. the set point
of the motor does not change,
so that the air flow rate remains
constant. In this mode, the display
reads:
“Nominal 3.0 m
3
/h real: x.xx m
3
/h”.
d) As soon as the connected calibra-
tion unit 16756 has stabilized and
displays a constant value, set this
value on the MD8 airscan by press-
ing
or
. Then confirm and
store it with Enter.
e) If this is not the last calibration
point, the next one is automatically
activated and processed as
described under a–d.
After the 7 m
3
/h value has been cal-
ibrated, the calibration is finished.
This is shown by the message
“Calibration completed (Enter)”.
f) Confirm by pressing Enter.
The MD8 airscan returns to the
initial starting position and is
ready to start.
Note:
If the calibration is interrupted
ahead of time, either the message
“User break!
(press Enter)” or “Overheated device
(Enter)” will be displayed. Confirm
this message by pressing Enter.
The MD8 airscan returns to the
initial starting position.
The altered calibration curve
is stored immediately when the
calibration has been finished or
interrupted.
6
Calibration of the MD8 airscan:
6.2. Resetting of Default Values
If, when calibrating the MD8
airscan, data were entered which
are so absurd that they make it
impossible for the instrument to be
controlled correctly by the phase
controller, it may be very difficult
to recalibrate correctly.
Even though this case is very
unlikely, because the consequences
would be serious, a hidden option
has been implemented in the MD8
airscan, allowing it to be reset to
its default values.
Procedure:
Switch off the MD8 airscan.
While holding down both the
and Stop keys simultaneously and
switch the MD8 airscan on. Do not
release the keys until the message
“Self-testing” is displayed.
Now press the
key while this
message is displayed.
Pressing of the
key must be
made while the “Self-testing”
message is displayed as only then
will the display change to “Delete
data? <Start> = yes”.
By now pressing Enter you confirm
this and all data will be overwritten
to the default settings. A self-test is
then re-started.
If you press any other key, instead
of Enter, the MD8 airscan will enter
its standard operating mode with-
out altering the data, in other
words, the unit is reset to the
default values.