Hanna Instruments HI 4521 User Manual
Page 29
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Clear Calibration
Accessing this option, the existent pH calibration can be cleared. If the calibration is cleared, another calibration
has to be performed.
To clear Calibration:
• Use
or
to select the Calibration option.
• Press
and use
or
to highlight the
Clear Calibration option.
• Press
to clear calibration. A pop-up menu will be
displayed asking for confirmation.
• Press
to confirm or press
to escape without
saving and return to the Calibration options.
Sample ID
This option allows the user to give to the measured samples an identification number/name. Two Sample ID
options are available:
ID Increment Mode and Edit Sample ID.
ID Increment Mode
Two increment modes for the sample ID can be selected:
None
–
the sample ID will be fixed and it can be set alphanumerically.
Automatic
–
the sample ID will be increased with 1 for each new log lot.
To set the ID Increment Mode:
• Use
or
to select the
Sample ID option.
• Press
and use
or
to highlight the
ID Increment Mode option.
• Press
and use
or
to highlight the
desired option.
• Press
to confirm your selection or press
to
cancel operation.
88
DIRECT/USP MEASUREMENT
In this measure mode the user can check for ultra pure water using the United States Pharmacopeia standard
(USP <645>).
This USP standard consists of three stages (one in-line and two off-line tests) as following:
Stage 1 - this is an in-line test.
To perform this test:
• Measure the temperature of the water and the uncompensated conductivity readings. The measurement
may be performed in a suitable container or as in-line measurement.
• The temperature will be round down to the nearest 5 °C and look up the corresponding conductivity value
in the below table.
• If the measured conductivity is lower than the conductivity in the table, then the water meets the USP
requirements.
• Otherwise, proceed to Stage 2 testing.
Stage 2 - this is an off-line test.
To perform this test:
• Store the water sample in an enclosed clean container that has been rinsed previously with water of the
same quality.
• Adjust the sample’s temperature to 25 °C and agitate the sample to ensure that it has equilibrated with
ambient CO
2
.
• If the measured conductivity is less than 2.1
µ
S/cm, then the sample has met the USP requirements.
• Otherwise, proceed to Stage 3 testing.
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