HF scientific 19944 Triple Validation Turbidimeter - 0-100 NTU - Manual (Page 16)

TVT2 (5/02)
Rev. 1.7 (.pdf) 11
5.1 Calibration Standards
We recommend that you use the following materials during calibration to achieve the
accuracy stated in this manual:
1. De-ionized water filtered through a 0.02 µm filter
2. 10.0 NTU Formazin primary standard, or 10.0 NTU pour through Calibration
Standard available from HF scientific, inc.
3. 100 NTU Formazin primary standard, or 100 NTU pour through Calibration Standard
available from HF scientific, inc.
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. A Formazin Stock Solution Kit is
available from HF scientific, inc. (Catalog No. 50040). The HF scientific, inc. calibration
standards (Catalog No. 19996) are more stable than Formazin and have a shelf life of 1
year. Prior to recalibration review the expiration date to ensure that the standards have
not expired.
5.2 Calibration Procedures
All TVT’s are shipped with a range of 0-10. A range of 0-100 NTU may be selected by
adding the included shorting strap (See section 7). If you did not request a measurement
range then you have a 0-10 NTU instrument. If you selected a range of 0-100 in section
7, then you should complete steps 7-10 using a 100 NTU standard first and then repeat
the steps with a 10 NTU standard.
1. Select the calibration function of the instrument by pressing the MODE button once.
The “CAL” block will be illuminated on the display with the turbidity value of 10.0
(or 100 for 0-100 NTU range) NTU displayed on the LCD. This is the first standard
that should be used in calibration.
2. Shut off flow to the instrument.
3. Disconnect the quick connects at the top and bottom to separate the instrument from
the process stream, then unscrew and remove the cleanout plug on the instrument.
4. Open the drain valve to allow the process water to drain from the sample well and
then close the drain. Capture this water in a container if spilt water is not wanted.
5. Pour 0.02 NTU or “turbidity free” water into the optical well and use the brush,
provided with the instrument, to clean out the sample well.
6. Drain the sample well and rinse the well at least twice with 0.02 NTU water.
7. After the sample well is drained close the drain valve and add 10.0 NTU calibration
standard to rinse out the optical well. Repeat this step and drain the optical well.