4: Performance Features & Safety Precautions; Hepa Filters - Labconco Logic+ 30348 Series User Manual

4: Performance Features and Safety
Precautions
All Cabinets operate using the following principles:
 Filtration and retention of particulates by High Efficiency Particulate Air
(HEPA) filter(s)
 Laminar airflow
 Directional airflow
The major components in a cabinet are:
 The HEPA filter(s) or optional ULPA filters
 The motor/blower to force air through the cabinet
 Cabinet air intakes (grilles), ductwork and air balance controls

HEPA Filters

HEPA filters are disposable, dry-type particulate filters. The filter material or media
is typically made of borosilicate microfibers formed into a thin sheet, in a process
similar to the production of paper. This sheet is folded, or pleated to increase its
surface area. The pleats are typically held in place by beads of glue that add
rigidity to the media pack. The pack is then set into a frame, and sealed as shown
in Figure 4-1.
The HEPA filter manufacturer establishes the efficiency of the filter by challenging
it with an aerosol of known particle size. The number of particles that penetrate the
filter are quantified, and this establishes the efficiency of the filter. Thus, the filters
used in the cabinet are at least 99.99% efficient in removing particles 0.3 micron.
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