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Density [ρ] of the measured medium
The density of fluids is temperature depen
-
dent. The density of most fluids decreases in
linear proportion to the temperature. However,
water reaches its highest density at 3.98 °C;
above and below this temperature, the density
of water decreases. This phenomenon is also
referred to as the “density anomaly of water�.
Make sure that the correct density of the measured medium is entered in the logger
software in order to calculate the level.
The density entered in the logger software is static. Changes in the temperature of the
measured medium and the associated change in density are not taken into account
when calculating the water level because this could result in misinterpretations of the
measurement result on account of the heterogeneous temperature distribution in bodies
of still water.
In normal cases, the temperature distribution is heterogeneous, so the temperature
dependency can be neglected. In case of homogeneous temperature distribution and
major temperature changes, however, a conversion error between pressure [bar] and
level [mWS] occurs due to the density that is stored as a static value.
(Water, temperature range 0...30 °C, pn = 1013 kPA).
Temp. [°C] Pressure
[bar]
Density [kg/m
3
] Calculated water level
Error at 5 mWS [cm]
4
0,5
999,975
5,0987 m
0 cm
10
0,5
999,702
5,1001 m
+ 0,14 cm
15
0,5
999,103
5,1032 m
+ 0,45 cm
20
0,5
998,207
5,1077 m
+ 0,9 cm
25
0,5
997,048
5,1137 m
+ 1,5 cm
30
0,5
995,65
5,1209 m
+ 2,22 cm
992.0
993.0
994.0
995.0
996.0
997.0
998.0
999.0
1000.0
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41
Density [kg/m3]
Temperature [°C]
Anomalous density
