AirUser 2008 96+4pp 23/7/08 16:51 Page 57
SECTION 6
Energy
Vaisala engineers a solution
Management &
Instrumentation
The Vaisala DRYCAP® technology was
developed according to customer needs to Vaisala DRYCAP®
measure low humidity with reliable
technology. Customer problems with low
key features:
humidity measurements, i.e. low dewpoint
measurements, related to poor accuracy.
• Dewpoint measurement at low
Vaisala professionals were able to solve the
dewpoints
challenges. • Excellent long-term stability Company name
• Fast response time
Vaisala Ltd.
OLD TECHNOLOGIES UNSATISFACTORY
There were some clear reasons why the then existing
• Recovers from saturation
Address
technologies could not offer better performance. The
Unit 9
traditional relative humidity instruments that
were successfully used for higher
Swan Lane
humidity measurements, typically
Exning
from ambient levels up to
Newmarket
saturation, were not accurate Suffolk CB8 7FN
enough in very low humidity,
where the relative humidity is
Contact details
approaching 0%RH. In terms of
uksales@vaisala.com
dewpoint, this means dewpoint
temperatures below -
Tel: 01638 576200
10 °C.
Fax: 01638 576240
Second, the typical
Country of
technology that was used for low
manufacture
humidity measurements was an
Finland
Aluminium Oxide sensor that was
sensitive enough down to very low
dewpoints (typically -70 to -80 °C Td).
Standards
However, it was also sensitive to ISO 9001
drift, which meant it required ISO 14001
calibrating several times per
AQAP2110
year to keep the ±2 °C Td
ISO/IEC 17025
accuracy. Continuous
calibration was costly and
(FINAS)
difficult.
Visit us today:
The third option was to use an www.vaisala.com/
analyzer type of instrument with a
compressedair
purchase price ten times that of a dewpoint
transmitter. A typical example of this is a
Vaisala DRYCAP® dewpoint products
www.vaisala.com/
condensation hygrometer that can offer very high
include a selection of instruments for fixed
dewpoint
accuracy (even up to ±0.1 °C Td), but only if regularly installations and portable use
maintained, typically daily.
SUPERIOR VAISALA MEASUREMENT FLEXIBLE TOOL FOR INDUSTRIAL
PERFORMANCE APPLICATIONS
With the new technology invented at Vaisala, all the Another important feature of the DRYCAP® sensor
problems of the old technologies were solved. The technology is that it works extremely well as a portable
DRYCAP® technology is based on a thin-film polymer tool, where the sensor is typically stored in ambient air
sensor. The polymer sensor is known to be a very and used only briefly to measure very dry gas or air.
stable and reliable technology. The DRYCAP® Thanks to DRYCAP® performance, the sensor adapts to
technology also applies autocalibration, a patented dry conditions very quickly.
key feature that eliminates the sensor drifting at the
dry end and allows dewpoint accuracy in the long- Vaisala DRYCAP® dewpoint sensor technology is used
term. This technology combination offers performance in industrial applications where the humidity of a gas,
that fulfills the market requirements, is easy-to-use, is typically air, is very low. Typical applications are in
cost-effective and has a very low need for compressed air or the plastic molding industry or in
maintenance. dry storage where the humidity is low (below 10%RH).
A special model for extreme temperatures up to
During the past 10 years a wide product range has +350 °C is also available for high-temperature drying
been built up utilizing the superior DRYCAP® processes.
measurement
performance. Today,
the technology is
available from a
small-size low-cost
dewpoint transmitter
to a dewpoint
transmitter with a
wide variety of
options, including
display, alarm and
Vaisala DRYCAP® is one of the most reliable dewpoint measurement technologies for low dewpoint
ENTER 82892
datalogging features.
measurements and Vaisala HUMICAP® for high dewpoint measurements
www.airuser.com/enquiry
AirUser 57
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