Specifications

13
HMI 38 Desktop Humidity Data
Processor/Calibrator
HMI 38 with probes
FEATURES/BENEFITS
 Portable, versatile and easy to use
 Six user-selectable outputs: relative humidity,
temperature, dewpoint, mixing ratio, wet bulb
temperature, absolute humidity
 System configuration and parameters can be set by
the user
 Data logging, built-in battery and optional carrying
case
 Two analog outputs and serial interface
 Optional cables for calibration function
 NIST traceable field calibrator
 Each probe supplied with NIST traceable
certificate of calibration
SIX OUTPUT VARIABLES
Up to two probes can be connected to the HMI 38.
The probes measure the relative humidity and
temperature of ambient air and, from these measure-
ments, the Humidity Data Processor then calculates:
 Dewpoint temperature
 Wet bulb temperature
 Mixing ratio
 Absolute humidity
Both metric and non-metric units are available.
VERSATILE AND EASY TO USE
The HMI 38 Humidity Data Processor is a micropro-
cessor-based instrument, which is ideal for measur-
ing humidity, related variables and temperature in
laboratories, storage areas, quality control areas and
air-conditioned areas, such as computer rooms and
cleanrooms.
The HMI 38 Humidity Data Processor can output six
different variables, either through its two analog
outputs, or via the RS 232C or RS 485 serial interface.
A built-in rechargeable battery provides power for
up to 8 hours of continuous use in the field.
The front panel menu guides the user through the
operation. The user can configure the measurement
system and the parameters controlling the HMI 38's
operation, so that the system and its operation can
be tailored to fit each application or any specific
measurement. The user can connect two probes to
each HMI 38 and choose which variables are needed
and the order in which they are displayed. The
display shows two variables at a time; to see the
others, simply scroll the display with the arrow keys
of the keypad.
DATA LOGGING AND DATA TRANSFER
The HMI 38 includes a data logging function. The
user can select the delay for starting the data logging
and the logging interval, or manually catch
individual measurements in memory.
The HMI 38 stores the relative humidity and tem-
perature measurements from both probes in
memory; from these values it calculates the other
variables when they are transferred to a computer or
a printer through the serial line. The user can define
the output format through the software to meet his
application needs.
All measurements are displayed on the LCD front
panel of the HMI 38 and output through the analog
output channels or to a printer or computer via the
RS 232C or RS 485 serial line. Measurement results
are output continuously or, upon request, via the
serial line. Several HMI 38 units can be connected to
one RS 485 serial line; each of them is given an indi-
vidual address.
USE AS FIELD CALIBRATOR
When used with an optional calibration cable, the
HMI 38 also serves as a one-point or two-point
calibrator for most Vaisala humidity and temperature
transmitters. It also provides an accurate field
humidity and temperature reference for other
manufacturers' instruments.
Select the right cable:
Instrument Calibration Cable Part No.
60/70 series 18300
230 series 18200
140 series 18300
20/30 series 18100