Hanna Instruments hi 93719 Manuale Utente

OPERATIONAL GUIDE

MEASUREMENT PROCEDURE

• Turn the meter on by pressing ON/OFF.

• When the LCD displays "- - -", it is

ready.

• Fill a graduated beaker to the

50 mL mark with the sample.

• Add 0.5 mL of HI 93719A Magne-

sium indicator solution, then swirl
to mix.

• Add 0.5 mL of HI 93719B Alkali

solution for Magnesium, then swirl
to mix.

• Fill two cuvets up to 1.5 cm

(¾") below the rim with 10
mL of sample each.

• Add 1 drop of HI 93719C EDTA

solution to one cuvet, replace the
cap and swirl the solution. This is
the blank.

• Add 1 drop of HI 93719D EGTA

solution to the second cuvet, re-
place the cap and swirl the
solution. This is the sample.

• Place the blank into the

holder and ensure that the
notch on the cap is posi-
tioned securely into the
groove.

• Press ZERO and "SIP" will appear on the display.

1.5 cm

OFF

ZERO

• Wait for a few seconds and the display

will show "-0.0-". Now the meter is
zeroed and ready for measurement.

• Remove the blank and insert

the sample into the instrument,
making sure that the notch on
the cap is positioned securely
into the groove.

• Press READ TIMED and the display will show the count-

down prior to the measurement. Alternatively wait for
exactly 30 seconds and press READ DIRECT. In both
cases “SIP” will appear during measurement.

• The instrument directly displays concentration in mg/L

(ppm) of magnesium hardness, as CaCO

, on the Liquid

Crystal Display. To convert the result to mg/L Mg,
multiply the reading by 0.243.

Note: the test will detect any calcium or magnesium contami-

nation in the mixing cylinders, measuring droppers or
sample cells. To test cleanliness, repeat the test multiple
times until you obtain consistent results.

SAMPLE DILUTION

This meter is designed to determine low levels of hardness,
typically found in water purification systems.
When testing some other sources of water, it is not uncom-
mon to come across levels of hardness that are greater than
the range of this meter.
This problem can be overcome through dilution. Dilutions
must be performed with hardness-free water or the readings
will be erroneous.
A dilution to reduce the level of hardness by a factor of one
hundred is performed as follows:
• Fill a 1 mL syringe with the sample.
• Place the syringe in a 50 mL beaker, making sure that

the beaker is clean and empty, and inject 0.5 mL into
the beaker.

• Fill the beaker up to the 50 mL mark with hardness-free

water.

Now, follow normal measurement procedure. The true value

READ

TIMED

The instruction listed below should be carefully followed
during testing to ensure best accuracy.
• Do not touch the cuvet walls with hands.
• In order to maintain the same conditions during the

zeroing and the measuring phases, it is necessary to
close the cuvet to prevent any contamination.

• Do not let the test sample stand too long after reagent

is added or accuracy will be lost.

• Whenever the cuvet is placed into the measurement cell,

it must be completely free of fingerprints, oil or dirt.
Wipe it thoroughly with HI 731318 or a lint-free cloth
prior to insertion.

• It is important that the sample does not contain any

debris. This would corrupt the readings.

• It is possible to take multiple readings in a row, but it

is recommended that a zero reading be taken for each
sample and that the same cuvet is used for zeroing and
measurement.

• It is important to discard the sample immediately after

the reading is taken because the glass might become
permanently stained.

• Shaking the cuvet can generate bubbles in the sample,

causing higher readings. To obtain accurate measure-
ments, remove such bubbles by swirling or by gently
tapping the vial.

• All the reaction times reported in this manual are

referred to 20°C (68°F). As a general rule of thumb,
they should be doubled at 10°C (50°F) and halved at
30°C (86°F).

TIPS FOR AN ACCURATE

MEASUREMENT

of the sample is the reading obtained multiplied by a factor
of one hundred (the dilution factor).
For your reference, factors to convert readings in mg/L to
French degrees (FD), German degrees (DD) and English
degrees (ED) of hardness are as follows:

1 mg/L = 0.1 FD = 0.056 DD = 0.07 ED.

INTERFERENCES

Interference may be caused by excessive amounts of heavy
metals.

Recommendations for Users
Before using these products, make sure that they are entirely suitable for the environ-
ment in which they are used.
Operation of these instruments in residential area could cause unacceptable interferences
to radio and TV equipments, 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 perform any measurement in microwave ovens.

ACCESSORIES

REAGENT SETS

HI 93719-01 Reagents for 100 tests
HI 93719-03 Reagents for 300 tests

OTHER ACCESSORIES

HI 710009 Blue rubber boot
HI 710010 Orange rubber boot
HI 721310 9V battery (10 pcs)
HI 731318 Tissue for wiping cuvets (4 pcs)
HI 731321 Glass cuvets (4 pcs)
HI 731325 Caps for cuvets (4 pcs)
HI 93703-50 Cuvets cleaning solution (230 mL).

CE DECLARATION

OF CONFORMITY

IST93719R1

06/98

PRINTED IN PORTUGAL