EUTECH INSTRUMENTS ?lpha-pH550, Instruction Manual, Page: 21 / 44

Instruction Manual
α
lpha-pH 550
Eutech Instruments
15
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
From pH measurement mode press CAL key to enter calibration mode
as described in section
1 1
4.2. The LCD shows ‘ CAL PH ’. Press ENT key
to begin calibration.
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
2
appears in LCD. Lower display shows pH 7.00 (USA
standard buffer). Upper display shows the current uncalibrated pH
reading. Allow the reading to stabilize. LCD shows ‘
READY ’ annunciator
when the reading is stable.
Press CAL key to confirm the reading.
The calibration is completed. The pH Monitor re-calculates electrode
properties based on the calibration. The new slope (in mV) is shown in
the upper display and pH reading at 0mV (pH7.00
±
offset) is shown in
the lower display.
3
Press ENT key to exit from the calibration.
The pH Monitor reverts to pH measurement mode.
4
Refer notes at the end of this section for additional information
and possible error indicators of calibration process NOTE: