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User's manual – Ver. 1.53 July 2015 11/75
actual flow – i.e., a ‘dynamic’ test. The point-to-point variation for the wavelength 880 nm at
the time-base set to one second is about 350 ng/m3, which translates to a couple of ng/m3 at
1 minute time resolution (Figure 4).
Figure 4. ‘Zero-air’ check – the Aethalometer Model AE33 switches form sampling ambient air to filtered
air – 1 second time resolution point-to-point variation is very stable.
The response of the optical detectors of the Aethalometer Model AE33 may be verified by use
of a standard kit of Neutral Density optical filters. These are glass elements with a range of
known and stable optical absorptions, from light to dark, which are traceable from
manufacturing records back to primary standards. When these are inserted into the AE33
Aethalometer, its photodetectors will give a certain output signal. The stability and
reproducibility of the relationship between optical signal and ND Filter density from one
validation test to another; and the comparison with the original factory values; is a measure of
the consistency of performance of the instrument’s optics.
User and Communications Interfaces
The Aethalometer Model AE33 incorporates the following user, data and communications
features:
1000 1500 2000 2500 3000
-1000
-500
0
500
1000
1500
2000
2500
3000
301 ng/m3
Point-to-point variation @ 1 second:
355 ng/m3
268 ng/m3
BC
(ng/m3)
t (s)
1 second timebase
30 point adjecent averaging
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