Thermo Scientific Orion 310, Instruction Manual

Page: 32 / 81

PerpHecT ® Orion 310, 320, 330 Instruction Manual
28 General Information on pH Calibration for Orion 320
Calibration and Measurement
A. Autocalibration with Two Buffers
1. Attach the pH electrode to the meter.
2. Choose either pH 4.01 and pH 7.00, or pH 7.00 and pH 10.01
buffers; whichever will bracket your expected sample range.
3. Press CAL key to initiate calibration sequence. CAL is displayed
for two seconds. Press the YES key to accept the last calibration
range (7-4 or 7-10) or select one of these calibration ranges using
the SCROLL (
▲
,
▼
) keys. Press the YES key to accept. The 7
buffer annunciator will light up. Place electrode in pH 7.00 buffer.
Reading will be displayed and updated as calibration continues.
When the READY light comes on, indicating electrode stability,
press the YES key to accept.
4. The pH 4 (or pH 10) annunciator will light up. Remove electrode
from pH 7.00 buffer. Rinse with deionized water and place
electrode in either pH 4.01 or 10.01 buffer (depending on
calibration range that was selected). When the READY light
comes on, press the YES key to accept buffer value. SLP will be
displayed while the calculated slope is displayed.
5. The annunciators for the type of calibration performed will remain
lit until another calibration is performed.
6. Meter will automatically go into the MEASURE mode. The
READY light will come on to indicate electrode stability.
7. If operating in the LogR mode or using an ATC probe, the
temperature-corrected pH reading is displayed.
8. Rinse electrodes with deionized water and place into sample.
Record pH directly from the main meter display when the READY
light is displayed or when electrode signal is stable.
NOTE:
When making measurements in LogR
mode, you must calibrate for temperature before
attempting a pH calibration. See page 33 for
temperature calibration procedure.