Hanna Instruments HI 83741 - Manual (Page 4)

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The HI 83741 is an auto-diagnostic portable microprocessor meter that benefits from Hanna’s
years of experience as a manufacturer of analytical instruments. It has an advanced optical system
based on a special tungsten lamp and a narrow band interference filter that allows most accurate
and repeatable readings. All instruments are factory calibrated.
The auto-diagnostic feature of this meter ensures always optimal measurement conditions to
ensure most precise readings. The light level is automatically adjusted each time a zero-measurement
is made, and the temperature of the lamp is controlled to avoid overheating.
GENERAL DESCRIPTION
Trace iron concentrations in wine are beneficial for enzyme activity, as stabilizer, and as a functional
component for proteins.
At higher concentrations it alters the redox potential, in favouring oxidation, affecting sensory
characteristics and participating in the formation of complexes with tannin and phosphates resulting
in instabilities (casse). The most common iron case is ‘white casse’ (iron phosphate), it is initially seen
as milky white cloud and later as a precipitate. The ‘blue casse’ (ferric tannate) that occours less often
can be observed in white wines for example after tannic acid additions.
Most of the iron present in wine is present in the ferrous Fe(II) state. The ratio of the Fe(II)/Fe(III)
depends on the oxidation state of the wine. If Fe(III) is formed, it can bind with phosphates that are
normally present in wine.
Since iron strongly binds with several organic acids, some wine makers add citric acid to the wine to
complex free iron if the concentration exceeds 5 mg/L.
If no contatamination occurs the normal iron concentrations in must range from 1 to 5 ppm. The most
important source of iron in wine is contact with iron containing alloys during processing. During
fermentation a part of the iron is absorbed by yeast and thus removed from the wine during filtration.
Casse formation depends on: iron concentration, pH, ORP, phosphate, content and the type of wine.
white casse formation white casse formation white casse formation white casse formation white casse formation white casse inhibition white casse inhibition white casse inhibition white casse inhibition white casse inhibition
iron concentration > 7 ppm iron concentration < 5 ppm
high redox potential (Fe3+ present) clarification with bentonite
pH 2.9-3.6 citric acid addition 12-24 g/hL
SIGNIFICANCE OF USE
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Recommendations for Users
Before using these products, make sure that
they are entirely suitable for your specific
application and for the environment in which
they are used.
Operation of these instruments may cause
unacceptable interferences to other electronic
equipments, this requiring the operator to take
all necessary steps to correct interferences.
Any variation introduced by the user to the
supplied equipment may degrade the
instruments' EMC performance.
To avoid damages or burns, do not put the
instrument in microwave ovens. For yours and
the instrument safety do not use or store the
instrument in hazardous environments.
CE DECLARATION OF CONFORMITY
HI 83741 is warranted for two years against defects in workmanship and materials when used for
its intended purpose and maintained according to the instructions.
This warranty is limited to repair or replacement free of charge.
Damages due to accident, misuse, tampering or lack of prescribed maintenance are not covered.
If service is required, contact your dealer. If under warranty, report the model number, date of
purchase, serial number and the nature of the failure. If the repair is not covered by the warranty,
you will be notified of the charges incurred.
If the instrument is to be returned to Hanna Instruments, first obtain a Returned Goods Authorization
Number from the Customer Service Department and then send it with shipment costs prepaid.
When shipping any instrument, make sure it is properly packaged for complete protection.
To validate your warranty, fill out and return the enclosed warranty card within 14 days from the
date of purchase.
Hanna Instruments reserves the right to modify the design, construction and appearance of its products
without advance notice.
WARRANTY