4
2.
Operation and installation
2.1. General informations
Water in hydraulic- and lubricating oil is a fluid contamination, which has to be limited
urgently due to its negative effects on the characteristics of fluids. Among other effects, it
does accelerate oil aging, it causes the failure of polarizing additives, it increases the acid
number and it worsens filterability. Effects for a hydraulic or lubricating system are very
manifold and cause significantly increased wear, drastically increased risk of failure of
components as well as malfunctions.
Important for these effects of water is whether water present in the fluid is free or
emulsified, not the total amount of water. Only free water does have the dangerous
chemical or biological reactivity. Therefore the detection of the presence of free or
emulsified water in a hydraulic or lubricating system is of great importance.
2.2. Measuring principle
The
WSPS 05
does utilize a
capacitive sensor
for measurements.
It uses polymeric foil as dielectric for interelectrode capacitance.
This foil is capable of absorbing water molecules due to its microporous structure.
This absorption causes a change in capacity of this element, which is converted into the
output signal
between
4 and 20 mA
.
Measurements are the
water
saturation
of the fluid in
percent
, which is direct proportional
to the output signal of the sensor. (see also the characteristic of the sensor in chapter 5.4)
In addition to that a temperature sensor is integrated to determine the exact temperature of
the fluid while measuring.
There is a difference to the measurement of the absolute water content with the
Karl-
Fischer-method
. The Karl- Fischer-method determines the total amount of free and
emulsified water in
mg
– water
/ kg
– oil
.
The
WSPS 05 gives the saturation level of the fluid with water in
percent
.
The indication
100 %
means that the fluid is totally saturated.
Saturation values depend on the temperature!
A relation to the measured saturation values and the stated ppm (mg / kg) value according
to Karl Fisher
’s method is ascertained by the 100 % saturation curve (100% of saturation =
f(T)) for the measured fluid and the fluid temperature measured at the same time with the
saturation.
