Hach-Lange PHC725 - Manual (Page 8)

5. Select Measurement Options and update the settings:
Option Description
Resolution Set the resolution:
• 0.1 pH—Fast
• 0.01 pH—Fast (default)
• 0.01 pH—Medium
• 0.01 pH—Slow, or
• 0.001 pH—Slow
The resolution has an effect on the number of decimal digits and the
stabilization time. More stabilization time is necessary for higher resolution
measurements. Slower stabilization times give higher accuracy
measurements.
Measurement
Limits Set the measurement limits—Lower limit (default: 0.00 pH) or Upper limit
(default: 14.00 pH).
Set the measurement limits to agree with the permitted values for the
sample. When the measurement is above the upper limit setting or below
the lower limit setting, the meter shows an "Out of limits" message. This
message is an alert to a possible problem with the process conditions.
6. If prompted, enter a name for the new method settings. Other changes made to the
settings of an existing method are automatically saved with the same method name.
7. Push EXIT until the meter goes back to the measurement mode.
Change calibration options
1. Make sure that a probe is connected to the meter.
2. Push and select PHC725 Settings.
3. Select Modify Current Settings.
4. Select Calibration Options and update the settings:
Option Description
Buffer Set Sets the temperature compensated buffer set for calibration:
• Color Coded—4.01, 7.00, 10.01 (default)
• IUPAC—4.01, 7.00, 10.01, 12.45
• DIN—4.65, 9.23
• IUPAC—4.01, 6.86, 10.01, 12.45
• IUPAC—4.01, 6.86, 9.18, 12.45
• IUPAC—4.01, 7.00, 9.18, 12.45
• Custom Buffer Set (refer to Table 3 )
Custom buffer sets are characterized at 25 °C (77 °F).
Buffer set values show on the Calibration Options screen.
Note: Measure only the minimum calibration points specified in Minimum
Cal Points to complete a calibration.
Buffer Set
Values Sets the buffer values if Custom Buffer Set is selected (refer to Table 3 ).
Minimum Cal
Points Sets the minimum number of calibration points that are necessary to
complete a calibration—1 (default), 2 or 3.
Slope Limit Sets the slope limit—1% to 20% (acceptable slope criteria, default = 15%).
Set the slope between the set limits for a correct calibration.
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