User Guide

12
ON
OFF
pH
HI 93725
pH & Total Hardness
REQUIRED REAGENTS
Code Description Quantity
HI 93710-0 pH Phenol red 5 drops
HI 93719A-0 Ca & Mg indicator 0.5 mL
HI 93719B-0 Alkali solution 0.5 mL
HI 93719C-0 EDTA solution 1 drop
HI 93719D-0 EGTA solution 1 drop
REAGENT SETS
HI 93710-01 Reagents for 100 pH tests
HI 93710-03 Reagents for 300 pH tests
HI 93719-01 Reagents for 100 hardness tests
HI 93719-03 Reagents for 300 hardness tests
For other accessories see page 48.
MEASUREMENT PROCEDURE
• Turn the meter on by pressing ON/OFF.
• The meter will automatically default to pH mea-
surement mode.
• When the LCD displays “- - -”, it is ready.
pH MEASUREMENTS
In order to perform pH measurements, follow the procedure on
page 46.
HARDNESS MEASUREMENTS
• Press pH/HARDNESS to select the Hardness range (the LCD
displays "ZER1").
• Follow the procedure on page 39.
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• Pressing READ will result in the meter scrolling
through the hardness concentration in mg/L
(ppm) by first displaying the Magnesium (n),
then the Calcium (C) and then the Total (t).
• By pressing ZERO the meter will be reset and be
ready for another test of Hardness.
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 uncommon 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 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.
ZERO
Hardness