Campbell Scientific SI-111 (IRR-P) Precision Infrared Radiometer - Manual (Page 15)

SI-111 Precision Infrared Radiometer
*Table 2 Program
02: 0.0
Execution Interval (seconds)
*Table 3 Subroutines
End Program
6. Maintenance
A primary source of inaccurate measurements for any radiation sensor is
blocking of the optical path to the detector. The window in the Apogee’s
infrared sensor is inset and protected, but it can become partially blocked in
three ways:
1. Spiders can make a nest in the entrance. We recommend using a cotton
swab to apply a spider repellent around the entrance to the aperture (not on
the sensor window itself).
2. Calcium deposits can accumulate on the window if irrigation water sprays
up on the head. These typically leave a thin white film on the surface and
can be removed with a dilute acid like vinegar. Calcium deposits cannot
be removed with solvents such as alcohol or acetone.
3. Dust and dirt can be deposited in the aperture in windy environments and
are best cleaned with deionized water, rubbing alcohol, or in extreme
cases, acetone.
Clean the inner threads and sensor window using a cotton swab dipped in the
appropriate solvent. It is important to use only gentle pressure on the window
to avoid scratching the thin optical coating on the window. Let the solvent do
the cleaning, not mechanical force. The cleaning should be repeated with a
second, fresh cotton swab to ensure a completely clean window. Sensors can
go for many months and stay clean in some environments, but frequent
cleaning is needed in other environments.
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