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User's manual – Ver. 1.53 July 2015 68/75
6.5 Manual clean air test
Clean air test is conducted using the built-in filter to determine the performance of
Aethalometer under the standard flow condition.
To perform the clean air test, select Operation/General/Clean air test. Test runs for 20
minutes at 5 lpm and 1 s time resolution. Clean air test is marked by status 2048. After the
test a report is generated:
Clean air test report.
Serialnumber: AE33-S02-00232
Date and time: 01 Dec 2014 13:41:03
Duration: 00:20:00, Timebase: 1 sec, Flow: 5000 mlpm
AverageBC PPBC (ng/m3)
Spot1 Spot2 Spot1 Spot2
Ch1 92 160 193 398
Ch2 38 76 255 592
Ch3 37 89 268 600
Ch4 46 128 307 672
Ch5 47 108 308 668
Ch6 24 94 385 848
Ch7 32 107 437 916
Result of clean air test is acceptable.
Interpretation of the results:
- Average BC values should be close to zero if the Aethalometer is warmed up (was
measuring for a few hours just before conducting the test). It is possible to observe a
short transient due to filter compression.
- Point to point variation of BC (PPBC) is calculated as an average absolute difference
between the consecutive BC measurements. It depends on the selected timebase, flow
and tested channel. A test criterion for 1 s time-base test at 5 lpm flow is: PPBC61 < 550
ng/m
3
.
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