Hanna Instruments HI 96719 - Manual (Page 14)

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• Remove the blank and insert the sample
into the instrument and ensure that the
notch on the cap is positioned securely
into the groove.
• Press and hold READ/ /TIMER for three
seconds. The display will show the
countdown prior to measurement. The
beeper is playing a beep at the end of
countdown period.
Alternatively, wait for 30 seconds then
just press READ/ /TIMER.
In both cases, the lamp, cuvette and
detector icons will appear on the display,
depending on the measurement phase.
• At the end of measurement, the instrument
directly displays concentration in mg/L
(ppm) of magnesium hardness, as CaCO
3
,
on the LCD. To convert the result to mg/L
Mg, multiply the reading by 0.243.
Note: the test will detect any calcium or magnesium contamination 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 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 erroneus.
• 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.