Specifications

25
HMP 228 for Direct Measurement of
Moisture in Oil
Vaisala's HMP 228 moisture transmitter enables fast
and reliable on-line water detection in oil for various
applications including lubrication systems and
transformers. It also enables you to monitor function-
ing of a separator or a purifier for example.
FEATURES/BENEFITS
 HUMICAP sensor, 25+ years of proven field perfor-
mance.
 Continuous moisture measurement in oil.
 Full measurement range of water activity 0...1.0
 Excellent long-term stability.
 Easy to install, calibrate, and maintain in the field.
 NIST traceable (certificate supplied).
CUT COSTS WITH MOISTURE
MEASUREMENTS
Moisture in oil has a great affect on its environment.
Water is the number one contaminant in lubrication
systems and it causes corrosion especially during
machine stoppages. Close detection of moisture
prevents interruptions and helps cut maintenance
costs. Thus the moisture content in lubrication systems
should be kept as low as possible.
RUGGED AND VERSATILE
Vaisala's HMP 228 transmitters can be supplied with a
cover which has a local display/keypad. The display
shows the measurement readings and also functions
as a user interface. A display/keypad transmitter is
easy to use and configure with the menu-based
commands of the built-in software.
The microprocessor-based transmitters measure water
activity (aw) and temperature (T). The transmitters
have two analog output channels and any two of the
measured or calculated variables can be selected as
output signals.
MEASURING WATER ACTIVITY
The primary measured variable in the HMP 228 is
water activity (aw) which has several advantages
compared to the traditionally measured variable, parts
per million by weight (ppm
w
).
The most important advantage is that the measured
water activity value directly indicates whether the oil
is too moist. Separate tables for different oil types are
not needed, nor are estimates of oil temperature, age
or conditions where it has been used.
INSTALLATION OPTIONS
The transmitter can be ordered with a ball valve set
that enables insertion and removal of the moisture
probe for calibration without the need to empty the
oil system.
ALARM RELAYS
For applications where adjustable on/off alarm
control is needed, the alarm relay option is the
solution. Alarm relays include two SPCO (single pole
change over) type relays with 8A / 230V contacts.
They are easy to adjust with display keypad or
through RS 232.
CONNECTORS
The transmitter has several different connector
options for analog output signals, supply voltage (24
VAC/VDC) and RS lines (RS 232C/422/485). The
connectors have the EMC and IP65 protection as well
as easy screw connections.
CONNECTORS
 Transformer oil monitoring
 Lubrication systems monitoring (e.g. pulp and
paper industry)
 Food oil processing
 Oil tank monitoring
 Mon-explosive fuel oil monitoring
HMP 228