12
13
Conductivity Calibration
Ideally, you should select a conductivity standard with a value near the sample
value you are measuring. The next best method is to choose a calibration solu-
tion value that is approximately
2
⁄
3
the full scale value of the measurement
range. For example, in the 0 to 1999 µS range, use a 1413 µS solution for calibra-
tion. Conductivity standards which are lower than 20% of the range should not
be used for calibration. It is not possible to make adjustments for values which
are in the lower 20% of the working range. See “Specifications”, page 21.
Preparing the Meter for Conductivity Calibration
You can calibrate at one point per range of the meter (a total of up to four cali-
bration points). However, only the ranges that have been calibrated have maximum
±1% full-scale conductivity accuracy. If a range was not calibrated, the meter automati-
cally detects the closest range calibrated and uses that calibration information.
To maintain ±1% F.S. accuracy, you need to calibrate your meter at least
once a week if:
• you take measurements at extreme temperatures
• you are measuring in conductivity ranges lower than 100 µS
To maintain ±1% F.S. accuracy, you need to calibrate your meter at least
once a month if:
• you are measuring in mid range solutions, and you wash the cell in deionized
water between usages.
The conductivity of solution varies greatly with temperature. The automatic
temperature compensation (ATC) feature adjusts the fluctuations of conductivity
readings in varying temperatures to a standard temperature. These conductivity
meters feature a temperature coefficient of 2.00% per °C and normalize the
readings at 25°C.
Calibrating for Conductivity:
1.
Pour out two separate portions of your calibration standard and one of
deionized water into separate clean containers.
2.
If necessary, press the MODE key to select Conductivity Mode
. The µS or
mS indicator will appear on the right side of the display.
3.
Rinse your probe
with deionized water, then rinse the probe in one of the
portions of calibration standard.
4.
Immerse the probe into the second portion of calibration standard.
The
meter’s autoranging function selects the appropriate conductivity range (four
ranges are possible). Be sure to tap the probe to remove air bubbles. Air bubbles will
cause errors in calibration.
5.
Wait for the reading to stabilize.
The
READY indicator lights when the reading
is stable.
See figure
6.
Press the CAL/MEAS key.
The CAL indi-
cator appears above the primary display.
The primary display shows the factory
default and the secondary display shows
the temperature.
See figure
7.
Press the
▲
or
▼
keys
to scroll to the
value of your conductivity standard. Press
and hold the
▲
or
▼
keys to scroll faster.
The meter automatically compensates for
temperature differences using a factor of
2.00% per °C.
See figure
8.
Press the ENTER key
to confirm
calibration.
Upon confirmation, the CON indicator
appears briefly. The meter automatically
switches back into Measurement mode. The
display now shows the calibrated, tempera-
ture compensated conductivity value.
See figure
9.
For calibration in other ranges
(maximum: four ranges) repeat steps
1 through 9 with the appropriate
calibration standards. See pages
22-23 for our selection of high-quality
OAKTON conductivity calibration
solutions.
Notes
To exit from Conductivity Calibration mode without confirming calibration,
DO NOT press ENTER in step 8. Press CAL/MEAS instead.
If the calibration value input into the meter is different from the factory default
value displayed by more than 30%
, the ERR annunciator appears in the lower left
corner of the display. Clean probe with alcohol. Verify that your calibration standard
is fresh and accurate.
4.4
ATC
CAL
mS
CON
C
D
D
ATC
CAL
mS
C
C
C
ATC
CAL
mS
READY
C
B
ATC
READY
MEAS
mS
C
A
B
A
