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"Scientists at The Air Space Technology Department of Politechnic of Milan
University pioneered a new approach in April 2000 using illumined dust
particles to precisely measure the ‘footprint’ of air flow throughout
the SAS air sampling process..." From Bioscience World,
Winter 2003
No Turbulence
By Guido Casati, International pbi
Scientists at The Air Space Technology
Department of Politechnic of Milan University pioneered a new approach in
April 2000 using illumined dust particles to precisely measure the
‘footprint’ of air flow throughout the SAS air sampling process.
Their method supplements previous research performed in smoke studies
documenting the excellent performance of SAS in critical control
environments.
Enclosed in a darkroom, they projected a light beam from a 575 Watt lamp
with an iris diaphragm to regulate the amplitude of the light cone and a
shaper to regulate the contour of the cone. Testing the air flow of the SAS
180, Duo SAS 360 and HiVac air samplers, they evaluated each sampler with
both 55 mm contact plates and 90 mm petri dishes.
Mounted on a floor tripod, each air sampler was tested 20 cm from the
light source at a fixed volume of 250 liters in an ambient temperature of 20
degrees Centigrade.
The SAS 180 and SAS Duo 360 systems showed that averages of the
turbulence at air inlet were ten to fifteen centimeters and at air outlet
were insignificant. The unidirectional flow was retained with the SAS 180
and SAS 360. The HiVac model exhibited an air cone of 15-30 cm due to its
side venting.
To achieve unilinear air flow, the SAS Air Sampler aspirates air at a
fixed speed through a solid stainless steel sampling head with 219 precision
drilled holes positioned over the agar at a prescribed distance. Upon
impaction, air flows over the agar’s dome shape and exits through an exhaust
screen. Accuracy is preserved by the consistency of the holes drilled into
rugged AISI 304 stainless steel, and the solid state electronics calibrated
to NIST traceability.
For More Information Contact:
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11607 Magruder Lane, Rockville MD 20852-4365
Tel: 301-230-0072
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Internet: BioInfo@Biosci-Intl.com
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