Hanna Instruments HI 95724 - Manual (Page 12)

12
MEASUREMENT PROCEDURE
• Turn the meter on by pressing ON/OFF.
• When the LCD displays “724”, it is ready.
• Do not let the reacted sample stand too long after reagent is added, or accuracy will be lost.
• It is possible to take multiple readings in a row, but it is recommended to take a new zero
reading for each sample and to use the same cuvet for zeroing and measurement.
• After the reading it is important to discard immediately the sample, otherwise the glass
might become permanently stained.
• 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).
• In order to maximize accuracy, prior to a measurement follow the validation procedure to be
sure that the instrument is properly calibrated. If necessary, calibrate the instrument.
• Fill the cuvet with 10 mL of unreacted
sample, up to the mark, and replace the
cap.
• Place the cuvet into the holder and ensure
that the notch on the cap is positioned
securely into the groove.
• Press ZERO and “SIP” will blink on the
display.
• After a few seconds the display will show
“-0.0-”. The meter is now zeroed and
ready for measurement.
• Remove the cuvet.
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• For free chlorine measurement: add 3 drops
of HI 93701A-T DPD1 indicator and 3
drops of HI 93701B-T DPD1 buffer to an
empty cuvet.
Immediately add 10 mL of unreacted
sample. Replace the cap and shake gently.
• Immediately reinsert the cuvet into the
holder and ensure that the notch on the
cap is positioned securely into the groove.
• Press READ and “SIP” will blink during
measurement.
• The instrument directly displays
concentration in mg/L of free chlorine on
the Liquid Crystal Display.
• Then, for total chlorine measurement, remove
the cuvet and add to the reacted sample 3
drops of HI 93701C-T DPD3 solution.
Replace the cap and swirl gently.
• Reinsert the cuvet into the holder and
ensure that the notch on the cap is
positioned securely into the groove.
• Wait for 2’ and 30” then press READ and
“SIP” will blink during measurement.
• The instrument directly displays
concentration in mg/L of total chlorine on
the Liquid Crystal Display.