Teledyne 633 Carbon Monoxide Alarm User Manual


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Model 633 Aethalometer
®
Black Carbon Monitor User Manual Teledyne Advanced Pollution Instrumentation
10 07645A DCN6170
2000 3000 4000
0
20000
40000
60000
80000
BC concentration (ng/m
3
)
time (sec)
IR, 1 second
raw BC1
raw BC2
compensated BC
Figure3.Thetimeseriesof633rawandcompensatedBCconcentrationswith1secondtimebase–note
theextremeconcentrationsandloadingeffects.
1.1.2 Automatic Zero and Span
TheModel633 Aethalometeris capableof automaticallycheckingthe‘zero‐air’ responseof
the instrument under dynamic operating conditions. This test is implemented by back‐
flushingtheinletconnectionwithanexcessflowofinternally‐filteredairandcirculatingthe
filteredairintheinstrument.Thedatareportedduringthisperiodareanalyzedforthemean
valueandthepoint‐to‐pointvariation. Themeanvalueshouldbeclosetozerounderideal
conditions;anypositivevaluegreaterthanzerorepresentstheleakageofBC‐containingroom
air into the instrument’s analytical zone. The point‐to‐point variation represents the
instrument’smeasurementnoiselevelunderactualoperatingconditionsofactualflow–i.e.,a
‘dynamic’test.Thepoint‐to‐pointvariationforthewavelength370nmatthetime‐basesetto
onesecondisabout125ng/m3,whichtranslatestoacoupleofng/m3at1minutetime
resolution(Figure4).
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