Chapter 4 _______________________________________________________________ Installation
VAISALA _______________________________________________________________________ 31
CHAPTER 4
INSTALLATION
This chapter provides information intended to help you install the
product.
Selecting Location
Finding a suitable site for Vaisala Present Weather Detector PWD22/52
is important for getting representative ambient measurements.
The main requirements for the location of PWD22/52 are:
1. Locate PWD22/52 a way that ensures measurements will be
representative of surrounding weather conditions.
- The ideal site for PWD22/52 has a minimum clearance of 100 m
from all large buildings and other structures that generate heat
and obstruct precipitation droplets. Avoid the shade of trees
because the trees may cause changes in the microclimate.
2. Ensure the site is free of obstacles and reflective surfaces disturbing
the optical measurement as well as obvious sources of
contamination.
- It is recommended that there are no obstacles in the line-of-sight
of the transmitter and receiver units (see Figure 7 on page 32). If
obstacles reflect the transmitter beam back to the receiver unit,
the sensor indicates too low MOR values because the reflected
signal cannot be distinguished from the actual scatter signal.
To detect reflections, rotate the sensor cross arm. Check the
visibility readings the corresponding visibility reading will
change depending on the cross arm orientation.
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