Vaisala HMT330MIK Technical data
20
Vaisala Instruments Catalog 2009
Ref. B210768EN rev. A
P.O. Box 26, FI-00421 Helsinki, Finland
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Email: industrialsales@vaisala.com
www.vaisala.com/HMT330MIK
HMT330MIK Meteorological Installation Kit
Features/Benefits
• For outdoor humidity and
temperature measurements
• Can be ordered in a variety of
congurations
• Used together with HMT337
transmitter or PTU307
• Vaisala SPH 10/20 Static Pressure
Head eliminates eectively pressure
variations in the barometer caused
by wind
HMT337 / PTU307 Features
• Warmed probe provides true
humidity readings in condensing
conditions
• Humidity measurement expressed
as relative humidity and/or
dewpoint temperature
• Easy eld calibration with the
e HMT337 and PTU307 feature warmed probe technology. Installed with the
HMT330MIK kit either one forms the right choice for reliable humidity measurement in
humid weather conditions.
HM70 hand-held meter
Tel. +358 9 894 91
Fax: +358 9 8949 2485
e Vaisala Meteorological Installation
Kit HMT330MIK enables the
Vaisala HUMICAP® Humidity and
Temperature Transmitter HMT337 to
be installed outdoors to obtain reliable
measurements for meteorological
purposes.
True humidity readings in
condensing conditions
In weather observations dew formation
makes reliable humidity measurement
dicult. When dew has formed on
the humidity sensor, it is impossible
to obtain a true reading until this dew
evaporates.
Both the PTU307 and HMT337
avoid this problem by warming the
probe. When warmed, the relative
humidity inside the probe stays below
the ambient level. With an accurate
temperature measurement, the
ambient dewpoint can be calculated
precisely. To obtain the ambient
relative humidity, an additional probe
measures the ambient temperature,
and the transmitter calculates the
relative humidity from the dewpoint
and temperature values.
After a period of 100 % relative humidity, the
warmed probe measures the true humidity,
whereas the non-warmed probe takes time
to recover from the condensation.
Open shield prevents
microclimates
e warmed humidity probe of the
HMT337 / PTU307 is mounted in a
shield which is open at the bottom to
ensure steady air circulation to the
sensor even in calm weather.
In traditional radiation shields sleet
or snow can accumulate on the shield
and prevent the proper air circulation
through the shield, and create a humid
microclimate until the snow melts.
Essential for critical
weather measurements
Obtaining a true humidity reading is
particularly important e.g. in trac
safety: at airports and at sea as well
as on the roads. It is essential, for
example, in fog and frost prediction.
For calibration, a portable HMP77
reference probe is easy to attach beside the
HMT337 or PTU307 probe.
21Vaisala Instruments Catalog 2009
Ref. B210768EN rev. A
HMT330MIK
Order form Valid from November 2006
Purchaser Order no.
Vaisala Meteorological Installation Kit HMT330MIK
PRICE
Support bar & shield for warmed Td probe
No support bar & shield for warmed Td probe 0
Support bar, transmitter mounting plate & shield for warmed Td probe 1
Support bar and radiation shield for
No support bar or radiation shield A
additional T probe or for
Support bar with DTR502 shield for T probe B
non-warmed RH or Td probe
Support bar with DTR13 shield for T probe C
Support bar with DTR502 shield for non-warmed RH or Td probe D
Support bar with DTR13 shield for non-warmed RH or Td probe E
Support bar mounting plate
No mounting plate 0
Pole mounting plate for support bar/bars 1
Additional transmitter mounting plate No additional transmitter mounting plate A
Transmitter mounting plate for support bar assembly B
Transmitter mounting plate for pole assembly C
Static Pressure Head No Static Pressure Head 0
Static Pressure Head SPH10 1
13
d
d
Dimensions
Dimensions in mm (inches).
HUMIDITY
DEWPOINT
BAROMETRIC PRESSURE
Order form
HUMICAP® is a registered trademark of Vaisala.
Specications subject to change without prior notice.
©Vaisala Oyj
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