MOISTURE MEASUREMENT IN OIL
Water is generally undesirable in hydraulic fluids and lubricants
and, in high concentrations, can cause enormous damage to
machines and systems. To avoid this, ipf electronic has added
the compact YF900020 oil moisture sensor to its portfolio,
which was developed to measure moisture in transformer,
motor, lubricating or hydraulic oil as well as diesel fuels.
The sensor has two freely configurable analog outputs
(4...20mA) and an RS485 interface with Modbus RTU, which
enable high-precision measurement of the water activity (aw)
and the process temperature (°C). In addition, the sensor also
calculates the absolute water content (x) in ppm (parts per
million). The device is mounted simply and securely via the
G1/2” process connection.
The YF900020 can withstand oil temperatures up to a maximum
of 125°C and operating pressures up to a maximum of 300 bar.
An additional interface adapter (VY000026) can also be used to
make changes to the Modbus settings, scale analog outputs or
assign measured values, for example.
SOME EXPLANATIONS WORTH KNOWING:
Water activity aw: The water activity aw is a relative measure
of moisture in oil. It describes the ratio between the actual
and maximum possible amount of dissolved water in the oil
at a certain temperature. The aw value indicates the degree
of saturation of the oil: aw = 0 (no water), aw = 1 (complete
saturation). The water activity is independent of the type of oil.
Water content x (PPM): The water content x is an absolute
measure and expresses the amount of water in the oil (dissolved,
emulsified or separated). The water content is measured in ppm
or milligrams of water per kilogram of oil and is independent
of the oil temperature. To assess the degree of saturation, x
must be considered together with the temperature (T). The
calculation of the water content x from the measured values for
aw and T is oil-specific and requires special parameters for the
respective oil. (bb)
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