Hanna Instruments HI 83749 - Manual (Page 11)

11
REMOVING AIR BUBBLES
Air bubbles present in the sample will cause erroneous high turbidity readings.
• To remove air bubbles fill the cuvet with wine sample and close the cap tightly. Shake the
cuvet gently to create pressure. Allow the cuvet to stand for a few minutes and gently invert it
several times. Check that no air bubbles are visible, otherwise shake again and repeat the
procedure above.
• Alternatively use an ultrasonic bath to degas the wine sample.
• In order to measure the exact volume of bentonite suspension with the 1 mL syringe, push the
plunger completely into the syringe and insert the tip into the solution. Pull the plunger up to
above the 0.0 mL mark. Take out the syringe and clean the outside of the syringe tip. Then,
adjust the plunger to the 0.0 mL mark (the lower edge of the seal must be exactly on the 0.0 mL
mark). Be sure that no drops are hanging on the tip of the syringe, if so eliminate them.
Then, to add exactly 0.25 mL of bentonite suspension, keep the syringe in vertical position over
the cylinder and push the plunger down until the lower edge of the seal is exactly on the 0.25 mL
mark. Now the exact amount of 0.25 mL has been added to the cylinder, even if the tip still
contains some solution.
Repeat the entire procedure to measure 0.50 mL, 0.75 mL and 1 mL of bentonite suspension.
MEASUREMENT TIPS
• For a correct filling of the cuvet: the liquid in the cuvet forms a
convexity on the top; the bottom of this convexity must be at the
same level of the 10 mL mark.
• For dosing the Bentocheck reagent, we recommend to use the
supplied Hanna automatic pipette (HI 731341 - 1000 µL).
For a correct use of the Hanna automatic pipette, please follow
the related Instruction Sheet.
0.25 mL 0.50 mL
or
Hanna
automatic pipette
30
alternated with
• Add HI 83749-0 Bentocheck reagent, mix and
wait for 1 minute. Then take a new reading (T2).
• If the difference between T1 and T2 is less than
10%, the instrument gives a beep of 1 second
and displays alternating the turbidity value
(NTU) and the difference (%).
• If the difference between T1 and T2 is more
than 10%, the instrument just displays T2 in
the primary LCD and T1 in the secondary LCD.
ACTIVATING COMPARATIVE MODE
For the determination of bentonite requirement you
can activate Comparative mode for an automatic
comparison of turbidity values.
• To edit the Comparative mode, press CAL/RCL
when “Activating Comparative mode” panel is
displayed.
The parameter setting and “CFM” tag will start
blinking.
• Press the UP or DOWN keys to set the
Comparative mode on or off.
• Press LOG/CFM to save the setting. The new
selected option will be displayed on the LCD.
Alternatively, press CAL/RCL to exit without
saving the new settings.
Note: when Comparative mode is set on, in the
Measurement mode, the secondary display will
show the reference value
or