31
Temperature Calibration
The temperature calibration should vary very little over the lifetime of the instrument
however it is worth checking on the accuracy of your temperature measurements
before calibrating the dissolved oxygen or salinity sensors.
Temperature calibration is performed at two temperatures. The low temperature must
be between 0 and 20 C and the high temperature must be between 30 and 50C. A
thermometer to at least 0.1
o
C accuracy and resolution must be used. To calibrate
temperature, proceed as follows:
1.
Select TEMPERATURE from the calibration key. The message CAL TEMP oC will
appear, press
ENTER
to calibrate or
ESC
to main menu. The message Cal high set
point or cal low set point (ENT/ESC) will appear. Press the ARROW keys to make
the selection then press
ENTER
to calibrate the low temperature range 0-20
o
C
press
ENTER
to proceed. Place the probe into stirred water bath. After pressing
ENTER,
Raw Data from the temperature sensor will appear, wait until the
readings are stable and make a note of the reading on the calibration
thermometer and press
ENTER.
Press the number arrow keys to change the
displayed temperature then press
ENTER
.
2.
If you proceed with the high range calibration, Select Cal high set point by using
the arrow keys. The message place probe into 25- 50
o
C water bath. Press
ENTER
,
the raw data D is displayed. Immerse the probe in a stirred water bath held at a
constant temperature between 25 and 50 C and wait for the probe to reach a
constant temperature. Make a note of the temperature on the calibration
thermometer and press ENTER. Use the silver
numbered
keys to change the
displayed temperature and press ENTER. The temperature calibration is now
complete.
High Conductivity/Salinity Calibration
The conductivity/salinity sensor is calibrated using solutions with a salinity of 0 ppt (air
calibration) and 35 ppt. Conductivity is a parameter derived from the salinity
measurement and so calibrating salinity simultaneously calibrates the conductivity
measurements. To calibrate the sensor, proceed as follows:
1.
First, ensure that the temperature sensor is reading accurately and, if necessary,
perform the temperature calibration described previously.
2.
Select calibrate Inst use arrow keys an select SAL (ppt) press ENTER use arrow
keys to select high or low calibration set points press (ENTER/ESC) will be
displayed. Press
ESC
to exit without changing the calibration.