1716
STANDARD SUSPENSION
Presently, there are only two recognized pri-
mary standards: AMCO-AEPA-1 and formazine.
HANNA instruments supplies HI 93703 with the
AMCO-AEPA-1 which has a much longer shelf
life at all concentrations (approximately six
months, if free from contamination). In addition,
no special handling or disposal is required and
a much higher stability of suspended particles
has been observed.
On the other hand, formazine is a very toxic
substance, generated by a known carcinogen,
its stability is poor (particles flocculate and
settle quickly). Lower concentrations change
value within a few days or hours after dilution
from stock solutions.
The consistency of HI 93703 readings by using
both standards has been separately estab-
lished by Advanced Polymer Systems and
HANNA instruments.
Additional documentation about the formazine
standard and more complex calibration proce-
dures is available upon request.
VIEWING THE CALIBRATION DATE
• Turn the meter on and
wait for the display to
show "----".
• Press and hold the
DATE/⇒ key and a
"MM.DD" message
appears while the key
is held.
Note: The displayed date is the date that was
input by the user at the beginning of the
last calibration.
HOW TO ENSURE ACCURATE CALIBRA-
TION
The instructions listed below should be carefully
followed during testing and during calibration:
• All glassware that comes into contact with
standards should be maintained clean. Wash
with HI 93703-50 cleaning solution and rinse
with HI 93703-0 or turbidity free water.
• Rinse the vial twice with 5 ml of the liquid to
be tested. This removes the effect of any
previous liquid and any dust or foreign matter
that may be present inside. Gently pour the
liquid down the side of the vial to reduce air
bubbles (no mixing is required when HI 93703-
0 and HI 93703-10 AMCO-AEPA-1 stan-
dards are used).
• Before inserting the vial
into the instrument,
wipe it with HI 93703-
70 soft, lint-free tissue.
Handle vials so that no
fingerprints can get on
the areas where light
passes (approx. 2 cm/
1'' from the bottom of
the vial ) .
(12 Seiten)
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