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Page 13
4. Conductivity (TDS/Salinity) Calibration
To achieve accurate Conductivity/TDS/Salinity results, the
WP-81
requires calibration to a known Conductivity standard. The TDS and
Salinity values are derived from the Conductivity reading and do not
require a separate calibration. The conductivity of a solution varies with
temperature. The
WP-81
uses Automatic Temperature Compensation
(ATC) referenced to the fixed temperature of 25
o
C.
A “
” in place of the decimal point indicates that the
Conductivity/TDS/Salinity readout is not calibrated, or a past calibration
has failed. The “
” will be removed once a Conductivity calibration has
been successfully performed in Conductivity standard.
4.1 Calibration Procedure
1. Plug the Conductivity sensor into the
Conductivity
socket.
If a k=0.1 or k=10 sensor is being used, ensure that the
WP-81
is set
to the correct k factor before using the instrument (see section 16).
2. Switch the meter on.
3. Rinse the Conductivity sensor in distilled water. Shake off as much
water as possible. Blot the outside of the sensor dry. DO NOT BLOT
THE SENSOR WIRES.
4.
Zero Calibration
Let the sensor dry in air.
Select Conductivity Calibration. (
F1:Cal.
F1:Cond.
)
5. When the reading has stabilised at or near zero, press the
key to
calibrate.
A “
“ will not be removed after a zero calibration.
6.
Standard Calibration
Allowable Conductivity standards are 150uS/cm, 1413uS/cm,
2.76mS/cm, 12.88mS/cm and 58.0mS/cm, and should be selected
according to your range of interest.
If the
WP-81
does not recognise the standard, it will display the
message, “
NOT STD
” during calibration. Calibration will fail if this
message is displayed.