Specifications

67
DMP 248 Dewpoint/Temperature
Transmitter For Low Dewpoint Applications
FEATURES/BENEFITS
 New DRYCAP
®
sensor for accurate, reliable, long-
term stability and fast response
 Unique automatic self-calibration
 User-programmable, versatile and easy to use
 Easy to install, calibrate, maintain
 NIST traceable (certificate supplied)
 Two analog outputs, serial interface
 Optional alarm relays, sensor re-gaining function,
local display, sampling system
DRYCAP
®
PERFORMANCE
DMP 248 transmitter incorporates the DRYCAP
®
thin
film polymer sensor and advanced software pro-
gramming. The combination makes the DRYCAP 248
dewpoint transmitter ideal for dry ambients. It offers
reliable, accurate measurements with excellent long-
term stability.
The DRYCAP® sensor is immune to particulate
contamination, water condensation, oil vapor and
most chemicals and can be used with confidence in
industrial environments. Since the sensor can
withstand condensation, its performance becomes
unmatchable for low dewpoint applications that
might see water spikes in the process. The sensor
will not only withstand free water contact, but will
rapidly recover 100% from such exposure, and
accurately monitor process dewpoints.
The DMP 248 provides Vaisalas most accurate and
stable measurement in dry ambients. The auto-
calibration, or self-evaluation, is done in-line, while
the process is running. If the measurement accuracy
is not confirmed, the software makes the corrections
to the calibration curve. The corrections may be due
to contamination or aging of the sensor. In either
case the transmitter adjusts the measurement and
continues to function. Calibration occurs so quickly,
and corrections are so minor, that the user will not
even realize it has taken place. Auto-calibration
parameters are set by the factory, but can be
changed by the user.
SETTINGS AND ADJUSTMENTS MADE EASY
Selecting, scaling and calibrating the analog output
signals and parameters can be done in minutes with
simple software commands.
DMP 248
These commands can be given, using the menus on
the local display, or with a PC or terminal connected
to the transmitters serial bus.
The microprocessor-based DMP 248 transmitter
measures water vapor pressure and temperature,
enabling it to display dewpoint, relative humidity,
ppm
v
and temperature. The transmitter has two
analog outputs and any two of the four measured
variables may be selected as output signals.
The transmitter software allows the user to perform a
one or two point calibration against relative humidity
references, e.g. Vaisalas electronic calibrators or
HMK 15 salt baths. The transmitter can also be sent to
Vaisala for a NIST traceable calibration. The calibra-
tion intervals depend on the application where the
transmitter is used. In normal conditions, calibration
once a year is recommended.