Catalog No. 29290
44
Rev 3 06/2020
4.3.6 Instrument Offset
•
Refer to section 4.2.5
•
It is possible to use an offset factor in the instrument rather than
performing a physical calibration.
•
This procedure is not recommended in lieu of regular instrument
calibration but it can be used to make the MTOL+ agree with another
instrument.
•
This calibration technique will make the instrument accurate
only
at
turbidity levels in the immediate vicinity of the grab sample and
not
in the
full range of the instrument.
•
Note that the
OFFSET
icon will be illuminated whenever an offset is used.
The maximum offset is ± 1.00 NTU.
•
If the instrument variation is greater than 1 NTU a full calibration is
recommended.
•
Below is the offset procedure:
1.
Collect a grab sample of the process water that is being monitored
by the MTOL+ and record the turbidity reported by the instrument.
2.
Take the grab sample and measure its turbidity using a laboratory
turbidimeter (contact the HF scientific customer services
department for examples of laboratory turbidimeters).
3.
Compare the turbidity reported by the MTOL+ to that obtained in
the laboratory. If the readings are very close, then no offset
adjustment or calibration is required and the procedure may be
stopped at this step. However, if the readings are substantially
different (but less than 1 NTU), continue on in this procedure to
utilize the offset option to improve the turbidity reading of the
MTOL+ so that it will agree with the laboratory reading between
calibrations.
4.
Select the offset function of the MTOL+ by pressing the
button
until the arrow beside
CONFIG
is illuminated on the display then
press the
button.
5.
Push the
button until
OFST
is displayed on the lower row.
6.
The upper row of the display will indicate the operational status of
the offset function (
On
or
OFF
). Change this status to
On
by using
the
and
buttons. Then press the
button to accept it and
move to the adjustment menu
7.
This will add or subtract the value of the offset to the measured
NTU value. As an example if the MTOL+ measures the process at
0.36 NTU but the laboratory instrument read the sample at 0.12
NTU, adding an offset of –0.24 would result in the MTOL+
displaying 0.12 NTU.
8.
Select the desired offset level using the
and
buttons. Once
the desired level has been set, press the
button to accept it.
9.
This completes the offset configuration.
Summary of Contents for HF scientific 28052
Page 2: ...Catalog No 29290 Rev 3 06 2020 ...
Page 5: ...Catalog No 29290 Rev 3 06 2020 ...
Page 66: ...Catalog No 29290 59 Rev 3 06 2020 ...
Page 67: ......