shows the filtration efficiency of the HEPA filter
and the Nylon 6 nanofilters as a function of face velocity.
The filtration efficiency of test particle can be calculated
by comparing with the particle number concentration between
upstream and downstream of the test filter medium
for the size range of each particle. The nanofilter sample 1
shows a good filtration efficiency to satisfy the criterion of
HEPA filter for the filtration efficiency of 99.97% at
0.3 lm particle size. At the condition of 10 cm/s of face
velocity, the filtration efficiency of nanofilter sample 1 is
decreased to 99.96% while the other filters still satisfy
the criterion of HEPA filter. As the velocity is increased,
collection by diffusion is reduced, but collection by
impaction rises. In the high velocity conditions, some
particles, acquired more momentum, pass through the filters
because of extremely thin thickness of the nanofilter
sample 1. On the other hand, the nanofilter sample 2,
which has double thickness to the sample 1, shows better
filtration efficiency than commercialized HEPA filter and
99.993% at 5 cm/s using 0.3 lm particle.