Thermo Fisher Scientific Alpha pH 550 - Manual (Page 21)

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NOTES:
•
To exit calibration mode at any time during calibration, press ▲
and ▼ keys simultaneously (escape). The pH Monitor returns
to the measurement mode and the old calibration values remain
active
• The calibration is always carried out in the units of
measurement (pH or mV), selected in setup mode
4.3 pH Calibration
The pH Monitor is capable of calibration of up to 2 points using USA or NIST pH
buffer standards. All new calibration values will automatically override existing
calibration data. pH buffer values are referenced to 25
o
C. Make sure the
measurement mode is set to pH. (Refer Section 5.5 for switching measurement
modes). All pH buffer values have window of up to
± 1 pH tolerance during
calibration. Calibration error can be occurred if the measured pH value exceeds this
window. If you wish to abort the pH calibration, press
▲ and ▼ keys simultaneously
and the pH Monitor reverts to pH measurement mode.
4.3.1 For USA Standard Buffer
Make sure that the pH Monitor is set to accept USA standard buffer in the Setup
mode. (Refer Section 5.4 for Buffer Selection Settings) The factory default is USA
standard. It is recommended that you perform 2-point calibration at room
temperature (25
o
C), starting with the first buffer at pH 7.00 followed by any other
buffer value. (pH 4.01, 1.68, 10.01 or 12.45)
1-Point Calibration:
CAL
HOLD
ENT
CAL
pH
READY
HOLD
pH
CAL
CAL mV
pH
HOLD
MEAS
PH
°C
ATC
READY ENT
1 2 3 4
1 1 From pH measurement mode press CAL key to enter calibration mode as
described in section 4.2. The LCD shows ‘CAL PH’. Press ENT key to
begin calibration.
2
Place the electrode in pH 7.00 buffer. Immerse the temperature probe in
the buffer solution if ATC mode is enabled. Immerse the potential matching
pin in the buffer if symmetrical mode is enabled. The buffer annunciator
appears in LCD. Lower display shows pH 7.00 (USA standard buffer).