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10. Measuring operations
10.4 Relative measuring
One very useful function is to zero the meas-
ured value at certain locations or at certain
times as a reference value in order then to
observe only the subsequent deviations. This
function is independent of the locking status
and does not modify the programming para-
meters in the connector. (Special cases,
see 10.5 and Locking, see 12.4).
To zero-set the measured value press key :
To display relative measuring with arrow :
Return to normal measured value by pressing and holding down key :
Setting to zero automatically deletes the maximum and minimum val-
ues for this channel. The MAX, MIN, and MEM functions are thus also
available for relative measurement.
10.5 Sensor adjustment
Many types of sensor need to be adjusted at least once or at regular intervals
to compensate for various instabilities. With dynamic pressure probes
(ranges L840 and L890, units Pa) the zero-point must be temporarily adjusted
by pressing key
With the following chemical probes automatic two-point adjustment can be
performed :
Probe
pH probe
Conductivity
O
saturation FY A640-O2:
2
1. Open locking
For adjustment purposes, since these sensors are by default locked, locking
must be temporarily deactivated. To do so when switching ON press and
hold down the two keys
up indicating that adjustment is now possible. After the device is switched off
the sensor will be locked again as normal.
2. Zero-point adjustment
To perform zero-point adjustment the measured value must first be phys-
ically set to zero, i.e.
● pH probe must be immersed in a buffer solution pH 7.0.
24
ALMEMO
, i.e. until switching off, even if the channel is locked.
CLR
Type
ZA 9610-AKY:
FY A641-LF:
FY A641-LF2:
FY A641-LF3:
MAX
2490
®
CLR
REL
Zero
Gain
point
7.00
4.00
pH or
10.00
pH
0.0
2.77 mS/cm
0.0
147.0 uS/cm
0.0
111.8 mS/cm
0
101 %
and
. The arrow FREE should then light
MIN
.
.
CLR
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