Turbidity measurement (VisoTurb
®
900-P)
Multi 3630 IDS
66
ba77170e03
10/2017
9.2.3 Calibration standards
Calibrate with 1 to 3 turbidity standard solutions. The standard solutions must
be selected in the following order.
The turbidity expected in the measurement dictates the number and selection
of the standards. Calibration has to be carried out for the range with the highest
turbidity to be expected and for all lower ranges. The standard solutions for this
have to be selected in ascending order, starting with standard 1.
Example:
If you expect turbidity values in the range 200 ... 4000 FNU/NTU, you have to
carry out a 3-point calibration.
The measurement precision is also dependent on the selected standard solu-
tions. Therefore, the selected standard solutions should cover the value range
expected of the turbidity measurement.
If the measured turbidity is outside the measurement range, OFL is displayed.
9.2.4 Carry out calibration
Standard solution
Range (FNU/NTU)
1
0.0 ... 1.0
2
5.0 ... 200.0
3
200.0 ... 4000.0
As the standard with turbidity value 0.0 FNU you can use clean tap
water or filtered, deionized water in a suitable calibration vessel,
depending on the required quality (see operating manual of the
sensor VisoTurb
®
900-P). This standard should be freshly pre-
pared prior to every calibration. Suitable bottles are listed in the
price list of the WTW catalog "Lab and field instrumentation".
Standards with turbidity values for the calibration ranges 2 and 3
are available as accessories (see price list of the WTW catalog
"Lab and field instrumentation"). Calibration can be carried out in
the bottles the standards are delivered in. The standards can be
used several times within their shelf life.
Replace the standards solutions if you have any doubts concerning
their quality or after the expiration date.
1
Perform the preparatory activities.
2
Connect the turbidity sensor to the measuring instrument.
The turbidity measuring screen is displayed.
3
Keep the standard solutions ready in suitable calibration vessels.
4
In the measured value display, select the TRB measuring window with
<
> <
>
and
<M>
.
