Calibration; Ph Calibration; Temperature Calibration - Oakton Acorn pH 5 series Operating Instructions Manual

4. Calibration

pH calibration

4.1
This instrument is capable of up to three-point calibration to ensure accuracy across
the entire range of the meter. You can perform 1-, 2- or 3-point calibration with
standard pH buffers 4.01; 7.00; and 10.00.
We recommend you perform at least a 2-point calibration at room temperature using
standard buffers that bracket (one above and one below) the expected sample range.
You can also perform a 1-point calibration, but make sure that the buffer value is
close to the sample value you are measuring.
All new calibrations will over-ride existing data.
NOTE: Do not reuse buffer solutions after calibration. Contaminants in the solu-
tion can affect the calibration, and the accuracy of the measurements.
Before use: remove the electrode soaker bottle. If the electrode has been stored dry,
condition the glass bulb by soaking it in tap water for 30 minutes. This hydrates the
glass bulb if the electrode is too dry, or has not been used for a long period of time.
1.
Turn meter on. Meter will automatically enter pH measurement mode.
2.
Rinse electrode thoroughly with deionized water or a rinse solution.
DO NOT wipe the electrode; this causes a build-up of electrostatic
charge on the glass surface.
3.
Dip both the electrode and temperature sensor into pH 7.00 buffer solution. The
glass bulb must be completely immersed into the sample. Stir gently, and wait for
reading to stabilize (approximately 40 seconds).
4.
Press CAL key to enter the calibration mode.
The display will momentarily flash "CA" to
indicate CAlibration.
A
See figure
The display will then show the current
noncalibrated reading, blinking while in
calibration mode.
B
See figure
5.
Allow the reading to stabilize. The meter auto-
matically recognizes 7.00, 4.01 or 10.00 buffers.
6.
Press ENTER key once to confirm calibration.
The LCD displays "CO" to indicate the calibra-
tion point has been confirmed. The meter exits
calibration mode and returns to measurement
mode.
8
A
B
pH
7.
Repeat with pH buffers 4.01 and/or 10.00
for best accuracy.
NOTE: This meter has automatic buffer recogni-
tion which identifies the correct pH buffer values
during calibration. If buffers other than 4.01, 7.00
or 10.00 are used, or the electrode has worn out,
the LCD will flash "Er1".
C
See figure

Temperature calibration

4.2
The temperature sensor included with your meter is factory calibrated. Over time,
the temperature calibration may drift and require recalibration. If you replace the
probe you should calibrate temperature prior to pH or mV calibration.
1.
Connect your temperature probe to the meter.
2.
Press the MODE/INC key until "°C" appears in the LCD.
3.
Compare displayed value to a NIST certified thermometer or other thermometer
known to be accurate. For best accuracy, place probe and thermometer in a
constant temperature bath.
4.
Press the CAL key. the LCD shows "CA" and
the reading flashes.
A B
See figures
5.
Press MODE/INC key until the display
shows the correct temperature. The MODE
/INC key will scroll to the maximum allow-
able value, and then loop back to the mini-
mum allowable value adjustment (maximum
adjustment is ±5°C from factory default).
6. Press ENTER key to confirm calibration.
The LCD displays "CO", and the meter then
reverts to measurement mode.
C
A
B
C
9