The particle size dependence of the collection efficiency of an environmental aerosol sampler

Evidence for long‐term changes in base cations in the atmospheric aerosol

“…The collection efficiency of the particulate sampler has been previously determined in a series of wind tunnel experiments using silica spheres from 4.5 to 25 [tm aerodynamic diameter and a density of approximately 1 g cm -3. The spheres were labeled with 212pb (half-life 10.6 h), and tests conducted at wind velocities in the range of 2 to 6 ms -1 [Pattenden and Wiffen, 1977]. At wind speeds up to 4 m s 'l, particles larger than 6 [tm were collected with 60% efficiency, but this fell to <15% efficiency for particles > 10 [tm.…”

“…At wind speeds up to 4 m s 'l, particles larger than 6 [tm were collected with 60% efficiency, but this fell to <15% efficiency for particles > 10 [tm. These sampling characteristics were noted to be similar to human inhalation [Pattenden and Wiffen, 1977] Cawse [1975] The numbers of "less than" values for each element, by year and site are given in Table 2. 3. Results…”

Sampling for Aerosols in the Ambient Atmosphere

“…In 1985, Barrett and his colleagues (Barrett et al, 1985) reported a similar study into the performances of a further pair of devices, this time with a view to their possible applications for the sampling of airborne lead. Pattenden and Wiffen, 1977) as well as similar ones intended for applications in workplaces (see Chapter 14). Like the four instruments described in the earlier 1984 study, both sampled omnidirectionally.…”

Summary of studies conducted under LANL subcontracts: 9-X73-4229J-1 and 9-XC3-9739K-1

“…Experimental and numerical results obtained by McFarland et al (4), Chandra (5) and Gong et 1 al. (6) showed th&tshrouded probes produce near-unity transmission ratio for operating conditio::s likely to be present in stacks like FE-15 and FE-16.…”

“…(3 He suggested that the entrance area should be as large as possible and the depth as small as possible for the most efficient sampling inlet. Pattenden and Wiffen (1977) concluded that the efficiency of sampling is not simply a function of strokes number but depends also on other parameters, including the airstream to inlet velocity ratio. They suggested investigating the effects of varying particle size, airstream velocity, inlet velocity, inlet diameter and angle of yaw.…”