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microAeth®AE51 Quick Start Guide microAeth®AE51 Quick Start Guide
Contamination, Maintenance & Cleaning of Sample Chamber
If a loose particle of contamination enters the microAeth AE51’s sample chamber or the
instrument experiences vibration or impact, the data will be degraded. Shaking or tapping
a “dirty” instrument will create data excursions that are far larger than those of a “clean”
unit. These effects are amplied greatly at the shorter timebase settings. Cleaning intervals
will vary based on the sampling environment and concentrations.
Contamination Probability for Various Use Scenarios
Sampling Scenario Contamination Probability
Dry, dusty environment High
Occupational settings with combustion exhaust High
Exposure to “oily” smokes such as biomass-burning
plumes, 2-cycle engine exhaust High
Presence of suspended uff, bers, pollen High
Immediate vicinity of trafc and roadways Medium
Outdoor urban environments Medium
Outdoor rural environments (without dust, uff, pollen) Low
Residential indoor environments Low
Recommended Hours of Operation Between Cleaning & Maintenance
Sampling Scenario Contamination
Probability
High Medium Low
Mobile sampling with impacts: on person or in vehicle 100 200 400
Mobile sampling on cushioned support 150 300 500
Stationary sampling, relocated during operation 500 800 1200
Stationary sampling, not moved during operation 800 1200 2000
NOTE: If a microCyclone™ is being used with your microAeth AE51, please clean it
on a frequent basis, depending on sampling environment and concentrations.
Operational Summary
• Always use a new lter strip for each measurement period.
• In order to get the best data from the microAeth AE51 for the sampling campaign, we
highly recommend that the instrument warm up for approximately 10-15 minutes so that
it can equilibrate to its environment.
• Leave the microAeth AE51 connected to the wall charger when not in use, to be sure
the battery is always fully charged and ready for use.
• Instrumental noise contributes a random perturbation to the ‘ideal’ BC data. Its
magnitude is inversely proportional to the operational parameters of timebase and
ow rate. These parameters should be set to values appropriate to the measurement
requirements and scenario.
• If the data exhibits noise that is unacceptable relative to the BC level being measured,
the noise may be reduced proportionally by taking the arithmetic average of successive
data values.
• Data collected on a rapid timebase is useful for identifying transient events of rapidly
changing BC concentration. Data collected on a 1 second timebase will almost always
require some subsequent smoothing and averaging. The 1 second timebase should be
considered as a ‘Data Acquisition Mode’.
• Vibration and impact may contribute transient changes to the light signal
measurements. These changes will appear as noise on the data, which may be
amplied if the instrument is operating at the shortest timebase setting.
• The instrument’s sample chamber should be kept clean and free of contamination in
order to minimize electronic noise and the possible effects of vibration and impact.
• Minimize transitions between environments of substantially different humidity. Avoid
placement near the vents of cycling air conditioning systems.
