17
Adjustment and Calibration
Measuring
By pressing the key
the user can select between all available channels of the
HDM97
.
These channels are
•
Conductivity and temperature
Display "CD/TEMP"
only Version
BN, BO, BP, BQ
•
Temperature
Display "TEMP"
only Version
BN, BO, BP, BQ
if enabled
•
Pressure
Display "PRES"
only Version
BH,
BM, BO, BP, BQ
•
pH
Display "PH"
only HDM97
BP
, if enabled
•
Flow
Display "FLOW"
only HDM97
BQ
, if enabled
•
Timer
Display "Time"
if enabled
Conductivity and temperature measurement
In this mode the display shows "CD/TEMP" in the upper line, the temperature value in the middle line and
the conductivity value in the bottom line.
→
CD/TEMP
(available in versions
BN
,
BO
,
BP
and
BQ
)
→
selection of conductivity temperature coefficient
→
reading min. value
→
reading max. value
Returns automatically back to measuring mode after 5 sec.
→
reset of both the min. and max. value
→
return to measuring mode
→
no function
Fundamentals of temperature compensation
Definition
Electrical Conductivity
Electrical conductivity or specific conductivity is a measure of a solution's ability to conduct an electric
current. Electrical conductivity of electrolytic solutions is strongly dependent on temperature. In order to
compare electrical conductivity measurements at different temperatures, they are standardized to a common
reference temperature. This common temperature is 25°C. The dimension unit commonly used is "mS/cm at
25°C"
Common temperature
The common temperature is the temperature at which non compensated conductivity measures and
compensated conductivity measures have the same value.
Temperature coefficient
The temperature coefficient is the relative change of the solution's conductivity depending on it's temperature
standardized to a common reference temperature. The dimension unit of this value is measured in %/K.