Hanna Instruments HI 93414 - Manual (Page 22)

22
MEASUREMENT PROCEDURE
TURBIDITY MEASUREMENTS
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. The current time appears
on the secondary LCD, if selected in SETUP
menu or “
turb” if the time is not displayed.
• 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 which
can influence the reading.
• Place the cuvette into the instrument. Align the
mark from the cuvette with the sign on the
instrument top 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 turbidity, free or total chlorine measurements, several basic rules should be followed:
• Always use cuvettes without scratches or cracks because they can cause inaccurate readings.
• Always cap the cuvettes to avoid spillage of the sample into the instrument.
• Always close 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.
• Always put 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 (for turbidimeter range only).