Specifications

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CUSTOMIZE YOUR INSTRUMENT
(Also see easy-to-use order form)
Vaisalas unique microprocessor design and
modularity allow you to customize the HMP 233
at time of purchase:
 Selection of output parameters:
- relative humidity - absolute humidity
- dewpoint - mixing ratio
- temperature - wet bulb temperature
- enthalpy
 Selection of temperature range
 Selection of:
- cable length (2, 5, or 10 meters)
- local display and keypad
- serial bus type (RS 232, 422/485 or digital current
loop
- type of sensor protection (variety of filter types
available)
- operating voltage 24 VDC, 115 VAC, 230 VAC,
50/60 Hz
After purchase, you can directly program either via
computer or local display and keypad:
 Units (metric or non-metric)
 The two output parameters corresponding to
analog channels 1 and 2 (note: all output para-
meters selected by users are also available via
serial output and display)
 Selection of the following output signals:
 4 to 20 mA  0 to 1V
 0 to 20 mA  0 to 5V
 0 to 10V
 Scaling of measurement parameters and output
signals (e.g. -10°C to +80°C corresponds to 0 to 5V)
FOR DUCTS & SMALL AREAS
The HMP 233 has been engineered for use in particu-
larly tight spaces, including chambers and incubators,
as well as for typical low temperature duct applica-
tions. Its small sensor head with its small thermal
mass is an advantage especially in situations where
the sensor head must respond quickly to surrounding
temperature changes. An optional kit consisting of
aluminum flange, lead-through piece, and steel
support bar enables installation of the HMP 233 in
ducts, channels, and through walls.
ON-SITE, ONE-POINT CALIBRATION
By utilizing a reference RH or temperature probe for
comparison, routine maintenance and calibration of
the HMP 233 can be performed on site within a
matter of minutes without disturbing transmitter
operation. This unique one-point calibration feature
will save down time, reduce service costs, and
ensure high accuracy operation.
HMP 233 Smart Humidity/Dewpoint
Transmitter for Measurement in
Ducts and Small Spaces
Incorporates Vaisalas next generation
HUMICAP® sensor.
Cable available in lengths of 2 meters, 5 meters
and 10 meters.
Supplied with NIST traceable certificate of
calibration.
Small sensor head/small thermal mass for fast
measurement in small spaces or chambers.
PPS grid with stainless steel netting and other
filters are available for sensor protection.
NEW FEATURES:
 Re-Gaining
This option makes the HMP 230 transmitters more
accurate and stable in environments where high
concentrations of chemicals or cleaning agents are
present. With Re-Gaining, activated by a software
command, the sensor returns to normal following
the evaporation of the chemicals from the sensor.
 Alarm Relays
For applications where adjustable on/off alarm
control is needed, this option is the solution. These
relays are easy to adjust with a display keypad or
through RS 232.
HMP 233