Figures & data
Figure 1. VBCS process diagram for the sampled air stream.
Figure 2. Schematic of the test apparatus.
Scheme 1. Typical experimental protocol for testing the VBCS.
Figure 3. Pressure drop as a function of filter face velocity for two common sampling filters and the RTI International's PU nanofiber filter in a 25-mm sampling cassette. Data points are an average of three measurements with the standard deviation in the measurements being the size of the symbols shown on the graph. Lines are to guide the eyes and are not fits or models.
Figure 4. Collection efficiency measurements for nanofiber filters at 25 L/min through 25-mm diameter filter. Data shown are the average of downstream counts to upstream counts with confidence limits calculated from Poisson statistics.
Figure 5. Particle transport. Observed particle losses and collection by system (measurement of aerosol concentration in the test rig compared with downstream of the filter holder with and without the collection filter installed). Data shown are the mean of particle counts downstream to the mean of counts upstream, with upper and lower confidence limits calculated via Poisson statistics.
Figure 6. Readout of filter and inlet environmental conditions for experiment of varying inlet conditions demonstrating the stability of conditions at the filter for transient inlet conditions. Data are from a single continuous experiment. Other experiments showed similar results. Due to the transient nature of the experiment, experimental uncertainty was not determined.
Table 1. Resulting filter conditions for different, steady-state inlet conditions for the VBCS. Data are from single experiments where values reported are the results after at least 30 min of consistent readings (coefficient of variation <1%) at each test condition.
Figure 7. Sampling of aerosolized E. coli with the VBCS. Data points are an average of 3 to 8 experiments, and error bars are the standard deviation. Bioaerosol was supplied during only the first 30 min of sampling. The relative culturability recovery is with respect to the AGI-measured, total aerosolized culturable bacteria present in the first 30 min.
