IS-HF-M100+-29293 Rev 4
8
Calibrating the M100+
The instrument was calibrated and tested prior to leaving the factory, so
it is possible to use the instrument directly out of the box. Under normal
conditions, recalibration is required once every three months. Quarterly
calibration ensures performance within accuracy specifications.
The EPA and ISO recommend that on-line turbidimeters used for
reporting purposes be calibrated with a primary standard at least once
every three months.
Calibration Standards
If the M100+ will be used over the entire range of 0.02 to 4000 NTU,
a complete calibration as described below will be required, which
includes two High Range standards.
If the instrument accuracy is only required below 1000 NTU, a
calibration may be performed using the 1000 NTU standard, the 10
NTU standard and the 0.02 NTU standard. To calibrate starting at 1000
NTU, simply press the 1000 button on the calibration screen.
If the instrument accuracy is only required below 10 NTU, such as for
potable water, a calibration may be performed using only a 10 NTU and
a 0.02 NTU standard. To calibrate starting at the 10 NTU, simply press
the 10 button on the calibration screen.
We recommend that the following materials be used during calibration
to achieve the full-scale accuracy stated in this manual. All calibration
standards listed below are available for purchase from HF scientific.
• High Range A ProCal Calibration Standard
• High Range B ProCal Calibration Standard
• 1000 NTU ProCal Calibration Standard
• 10.0 NTU ProCal Calibration Standard
• 0.02 NTU ProCal Calibration Standard
Diluted Formazin is unstable. If Formazin is used to calibrate the
instrument, ensure that a fresh stock suspension of Formazin
is used to achieve the accuracy quoted for the instrument. A
Formazin Stock Solution Kit (catalog no. 50040) is available from
HF scientific.
NOTICE
The HF scientific ProCal (Primary Calibration Standards) are more
stable than Formazin and have a minimum shelf life of 12 months. For
more information on ordering HF scientific's ProCal Standards, see
Accessories and Replacement Parts List later in this manual.
Prior to recalibration, review the expiration dates to ensure that the
standards have not expired.
Care of ProCal Standards
The information below is provided as general guidelines for proper care
of ProCal standards.
• Standards should only be handled by the top, black cap or by
the very bottom of the cuvette.
• Keep cuvette glass clean of fingerprints and debris.
• Cuvettes can be cleaned with any domestic glass cleaner and
the provided microfiber cloth.
• Prevent ProCal standards from freezing. This will most likely
destroy them.
• Standards under 100 NTU must be freshly poured from the
supplied bottle as they are not stable in the glass cuvette.
• There is no need to shake standards, but standards over 1000
NTU should be up-ended gently before use.
• Replace standards at the expiration date.
Indexing Calibration Cuvettes
To achieve the greatest accuracy and account for normal scratches
and aberrations in cuvette glass when calibrating, HF scientific
recommends indexing the cuvettes.
Standards and standards kits purchased from HF scientific are supplied
with indexing rings. Complete instructions on how to index cuvettes are
included in the calibration kits.
Indexing is best performed if the automatic reading is enabled and
set to 1 sec/reading. See Auto/Manual Readings section for more
information. The following steps allow repeatable indexing of calibration
standards.
1. With the instrument in the home screen, insert the standard.
2. Slowly rotate the standard inside the optical well one complete turn
(360°).
3. While rotating the standard slowing, observe the measured turbidity
and locate the position of the cuvette having the lowest reading.
4. With the calibration standard positioned at the location having the
lowest turbidity reading, install the indexing ring over the cap on
the standard so that the pointer of the indexing ring faces directly
forward.
When using the standards in the future, always insert the standard so
that the pointer of the indexing ring faces forward. Slowing rotate the
standard back and forth about 5° to find the lowest point. The standard
is now indexed and ready for use.
Calibration Procedures
To calibrate for 0-4000 NTU using ProCal, you will need the following
standards:
• High Range A
• High Range B
• 1000 NTU
• 10 NTU
• 0.02 NTU standards.
To calibrate for 0-4000 NTU using Formazin, you will need the following
standards:
• 4000 NTU
• 1000 NTU
• 10 NTU
• 0.02 NTU
Prior to beginning calibration, clean the calibration standard cuvettes
with a microfiber cloth and standard window cleaner. Take care to only
handle standards by the black cap to prevent fingerprints or smudges
from affecting the readings.
