Hanna Instruments HI 98703 - Manual (Page 19)

19
MEASUREMENT PROCEDURE
To take turbidity measurements, follow the next steps:
• Turn the instrument ON by pressing
ON/OFF.
When dashes are displayed on the LCD, the
instrument is ready. On the secondary LCD the
current time appears, if selected in SETUP menu.
• Fill a clean, dry cuvette with 10 mL of sample
up to the mark, taking care to handle the
cuvette by the top.
• Replace the cap.
• Wipe the cuvette thoroughly with a lint-free
cloth to remove any fingerprints, dirt or water
spots.
• Apply silicone oil on the cuvette and wipe with
a lint-free cloth to obtain an even film over the
entire surface of the cuvette.
Note: It is very important to oil the cuvette,
especially for low turbidity values (< 1
NTU) to hide the glass imperfections that
can influence the reading.
• Place the cuvette into the instrument. Align the
mark from the cuvette with the sign on the
instrument case and close the lid.
Note: If you have a cuvette with orientation mark,
place the cuvette into the instrument with
the orientation mark aligned with the sign
on the instrument top.
When taking any turbidity measurements several basic rules should be followed:
• Use always cuvettes without scratches or cracks because they can cause inaccurate readings.
• Cap always the cuvettes to avoid spillage of the sample into the instrument.
• Close always the lid of the instrument during measurement.
• Keep the lid of the instrument closed when it is not used to prevent dust or dirt entering.
• Put always the instrument on a flat, rugged surface when taking measurements.
• Do not operate in direct sunlight.
• Do not use too much oil to prevent contamination of the optical system.