Thermo Fisher Scientific TN100 Turbidimeter - Manual (Page 10)

Instruction Manual TN-100/ T-100
5
2. Turbidity Calibration
Calibration Overview
The TN-100/T-100 turbidity meter was calibrated and tested prior to leaving the factory.
The meter kit now includes a set of prepared SDVB primary standards in plastic bottles
which are EPA-approved for meter calibration. This keeps the stock solutions for the
0.02, 20.0, 100 and 800 NTU standards ready to use and offers improved precision
and shelf life. A set of 4 empty vials for the standards are included in the meter kit.
Before using the meter for the first time, verify the meter calibration by reading back the
value for the prepared primary standard at the appropriate NTU value. This check is
recommended daily to check the meter prior to measuring a sample. When the
standard value drifts, retest with a vial of fresh standard solution. The 0.02 NTU
standard needs to read <0.1 NTU for acceptance.
A replacement set of the 4 standards in plastic bottles is available. These 60mL bottles
are identical to the bottles in the meter kit, so they can easily be carried in the case to
where the measurement needs to be taken. These standards are specifically made for
the TN-100/T-100 portable turbidity meters. The standards will not read to the stated
NTU value in other manufacturer’s turbidity meters.
2.1
Calibration Standards
We recommend that you use the following materials during calibration to achieve the
accuracy stated in this manual:
 CAL 1: 800 NTU Calibration Standard
 CAL 2: 100 NTU Calibration Standard
 CAL 3: 20.0 NTU Calibration Standard
 CAL 4: 0.02 NTU Calibration Standard
It is well known that diluted Formazin is unstable. If you choose to use Formazin to
calibrate the instrument, ensure that you are using a fresh stock suspension of
Formazin to achieve the accuracy quoted for the instrument. Calibration standards
offered are more stable than Formazin. For expiry date of calibration standard, please
refer to the expiration date indicated on the cap label.
It is important that the calibration standards are not violently shaken or agitated
because air entrapment in the fluid introduces an error factor during calibration
which subsequently will lead to an inaccurate measurement. Also, do not store in
freezing temperatures which causes irreversible shrinkage of the standards’
particles thus resulting to inaccurate calibration and measurement.
2.2
Indexing
Due to the high quality of the glass vials provided, indexing is not required. You only
need to align the mark on the vial with the mark on the meter. However, in order to
achieve a better accuracy of the measurement, you can proceed with indexing of the
vials. See Section 8.5 - Indexing a Vial on page 20 for more information.