User`s guide

Chapter 4 _______________________________________________________________ Installation
VAISALA _______________________________________________________________________ 35
CHAPTER 4
INSTALLATION
This chapter contains information that is needed to install WMT700 with
the FIX70 mounting kit.
NOTE
If you are upgrading from WS425 to WMT700 and using a WS425
mounting kit, see Upgrading from Vaisala WINDCAP
®
Ultrasonic Wind
Sensor WS425 to WMT700 Technical Reference.
Selecting Location for Representative
Measurements
Finding a suitable site for WMT700 is important for getting
representative ambient measurements. The site should represent the
general area of interest. It is recommended that you follow the WMO
Guide to Meteorological Instruments And Methods of Observation
WMO-No. 8, or other application-specific requirements set by various
organizations, like ICAO.
It is important to take into account the geography and surrounding area to
achieve optimum performance. Trees, buildings, or other objects situated
in the vicinity of WMT700 disturb free air flow and thus affect the
accuracy of the measurement results.
Ideally, WMT700 should be higher than any other object within a
horizontal radius of 300 m. In general, any object of height (h) does not
remarkably disturb wind measurement at a minimum distance of 10 x h.
When mounting WMT700 on top of a building, the recommended
minimum height (h) for the mast is 1.5 × the height of the building (H).
When the diagonal (W) is less than the height (H), the minimum height
of the mast is 1.5 × W.
When there is a need to ensure free air flow with cross arm installation,
the distance (y) between WMT700 and the mast should be more than
20 × the diameter of the vertical mast (z). For more information, see