Biotech-Lab User Manual
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www.ibpmedical.com
7 Sensor Sub Menus
7.1 CONDUCTIVITY SENSOR DETAILS
The following menu shows the settings for conductivity sensors.
Head area shows the serial number and the date of last calibration.
Select the unit you like to see in the graphic here.
Allows selecting a higher resolution of the reading.
Allows selecting the conductivity temperature compensation coefficient
Allows entering a user specific value
Allows adjusting the conductivity.
Values on the right are the readings of current values.
7.1.1 BACKGROUND OF TEMPERATURE COEFFICIENTS
This is a topic that is frequently misunderstood and often neglected in haemodialysis.
A solution’s conductivity will change according to temperature. With increasing temperatures, the measured solution’s
conductivity will increase too. To achieve meaningful measurement results, the conductivity value displayed is compensated
to 25°C. In other words, the display is always converted to a solution temperature of 25°C. The temperature coefficient which
the displayed value is compensated with is expressed as %/°C. Unfortunately however, different solutions also have different
temperature coefficients. To achieve an exact reading, the instrument will have to be adjusted to the temperature coefficient of
the current solution. The commonly used temperature coefficient for dialysates is 2.07 %/K. For naturally occurring solutions,
a value of 1.97 %/°C is frequently used. Many measuring devices not specially tailored to dialysis will use this value.
Dynamic Temperature Compensation
Dynamic temperature compensation is achieved by calculating a temporary temperature coefficient for the measured
temperature using a set of two coefficients for 25°C and 37°C respective. This temporary temperature coefficient is then
applied to the actual measured conductivity to calculate the conductivity at the common reference temperature. The following
table shows the usage of dynamic temperature coefficients applied to a NaCl solution of 14mS/cm.
