Campbell Scientific CNR1 Net Radiometer - Manual (Page 8)

CNR1 Net Radiometer
Northern Hemisphere this implies that the Net Radiometer should be mounted
south of the mast.
It is suggested that the CNR1 is mounted at a height of at least 1.5 meters
above the surface to avoid shading effects of the instruments on the soil and to
promote spatial averaging of the measurement. If the instrument is H meters
above the surface, 99% of the input of the lower sensors comes from a circular
area with a radius of 10 H. Shadows or surface disturbances with radius
< 0.1 H will affect the measurement by less than 1%.
It is recommended that the CNR1 be mounted to a separate vertical pipe at
least 25’ from any other mounting structures. PN 14264 mounting bracket is
used to mount the CNR1 directly to a vertical pipe. Mount the sensor as
follows:
1. Attach PN 14264 mounting bracket to the vertical mounting pipe.
2. Insert the CNR1 mounting arm of the sensor into the 14264 mounting
block. Tighten the four set screws just enough to secure the mounting
arm position, but loose enough to allow the arm to be rotated.
Do not attempt to rotate the instrument using the sensor heads or
you may damage the sensors; use the mounting arm only. NOTE
3. Loosen the vertical adjustment screws on the back of the 14264 mounting
bracket. Adjust the sensor mounting arm horizontally and vertically until
the bubble level on the sensor head shows level. Tighten the adjustment
screws to secure the position.
FIGURE 3-1. CNR1 Mounting Options
For installation in buildings or in solar energy applications, one will often have
to mount the CNR1 parallel to the surface that is being studied. This may be in
a tilted or a vertical position. The sensitivity of the radiometers will be
affected, but only in a minor way. This is specified as the so-called tilt effect.
From the specifications one can see that the tilt effect (this is a change in
sensitivity) remains within 3 %.
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