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5
As a rule of thumb, it can be assumed that conductivity varies by 2% for each 1
C change in
temperature.
This means that a calibration solution rated 5 mS/cm (at 25
C) has a conductivity of
approximately 4 mS/cm at 15
C.
The table below lists several typical conductivity values for various types of water.
Type
Conductivity [mS/cm]
Tap water
0.2 0.7
Groundwater
2 - 20
Seawater
50 - 80
1.5.1
Specific Conductivity
The specific conductivity of an electrolyte solution is defined as the conductivity if the solution is at a
certain reference temperature. The specific conductivity is an indirect measure of the presence of
dissolved solids such as chloride, nitrate, phosphate, and iron, and can be used as an indicator of
water pollution.
The following equation is used for calculating the specific conductivity K
Tref
from the measured
conductivity K.
K
Tref
=
100
100+θ(T−T
ref
)
∙ K
(5)
where:
K
Tref
= Specific conductivity at T
ref
K = Conductivity at T
T
ref
= Reference temperature (25 °C)
T = Sample temperature
θ
= Temperature coefficient (1.91 %/°C)
Summary of Contents for CTD-Diver DI28 Series
Page 1: ...CTD Diver DI28x Series...