Hanna Instruments HI 93703 User Manual

Page 7

CALIBRATION

A monthly calibration is recommended. To
check the date of last calibration, simply hold
the DATE/

⇒

key down for few seconds.

A more frequent check of the instrument is
suggested by using the supplied standard solu-
tion.

CALIBRATION PROCEDURE

• Turn the meter on and

wait for the display to
show "----".

• Press the CAL key

once, the "CAL" mes-
sage will blink on the
display for about 6
seconds, then the
c a l i b r a t i o n m o d e
stops.

• While the "CAL" mes-

sage is still blinking,
press CAL again. The
instrument is now in
the calibration mode
and a "CL" will ap-
pear on the lower part
of the display. The
date of calibration can
be edited now by sim-
ply pressing the
DATE/

⇒

k e y . T o

scroll to the correct
number press the
READ/

⇑

key

The de-

fault blinking param-
eter is the month, on
the left hand of the
display (MM.DD).

SOURCES OF INTERFERENCE

• Presence of floating debris and coarse sedi-

ments which settle out rapidly will give false
readings.

• The infrared light source used for HI 93703

turbidity meter, according to ISO 7027 Inter-
national Standard, can effectively minimize
errors due to colored dissolved substances.
This effect, named "true color", is a common
interference for most commercially available
instruments operating in the range of visible
light.

• Air bubbles and the effect of vibrations that

disturb the surface of the sample will give
false results.

• Dirty glassware could also affect readings

along with scratched or edged vials.