48
SECTION 3,
continued
NOTES
•
If the
I/O
key is pressed during calibration, the new calibration data
is lost and the old calibration will be used for measurements. Once
in calibration mode, only the
READ, I/O,
↑
, and
→
keys function.
Signal averaging and range mode must be selected before entering
the calibration mode.
•
If
E 1
or
E 2
are displayed, an error occurred during calibration.
Check the standard preparation and review the calibration; repeat
the calibration if necessary. Press
DIAG
to cancel the error message
(
E 1
or
E 2)
.
To continue without repeating the calibration, press
I/O
twice to restore the previous calibration. If
CAL?
is displayed, an
error may have occurred during calibration. The previous
calibration may not be restored. Either recalibrate or use the
calibration as is.
•
To review a calibration, press
CAL
and then
↑
to view the
calibration standard values. As long as
READ
is never pressed and
CAL
is not flashing, the calibration will not be updated. Press
CAL
again to return to the measurement mode.
3.6.3.1
Preparing User-selected Formazin Dilutions
The formazin solutions should span the entire range of the instrument.
Hach recommends preparing three standards:
1.
10 to 30 NTU
2.
90 to 110 NTU
3.
700 to 900 NTU
The standards must have a difference of at least 60 NTU.
In addition, a blank made from the dilution water should be prepared.
Prepare the formazin standard solutions from the well mixed 4000 NTU
stock solution as specified in
Section 3.6.2.4
on page
42
and dilution
water as specified in
Section 3.6.2.2
and
Section 3.6.2.3
on page
41
.
Make the standards
immediately
before use and discard them after
calibration is done.
