A constant flow filter air sampler for workplace environments.
A filter air sampler has been developed for sampling radionuclide aerosol particles from the workplace environment. It provides easy filter changing, constant flow sampling, and a visual display to indicate proper operation. An experimental study was conducted to characterize the collection efficiency of the sampler as affected by variations in room air velocity, particle size, sampling flow rate, inlet geometry, and inlet orientation to the free stream. Tests were carried out in a wind tunnel at velocities between 0.3 m s(-1) and 2.0 m s(-1), which is a range that covers anticipated velocities in the typical highly ventilated workplace environment of a nuclear facility. Nearly monodisperse aerosols with sizes between 5 and 20 microm aerodynamic diameter were sampled at flow rates between 28.3 and 84.9 L min(-1). Inlet orientations of 0 degrees, 90 degrees, and 180 degrees from the horizontal were selected for evaluation. When the sampler was oriented at 0 degrees over various ranges of free stream velocities, sampling flow rates and particle sizes, the transmission efficiency of aerosol was typically greater than 95%. The transmission efficiencies varied from 80% to 106% for 10-microm aerodynamic diameter particles over the previously noted range of free stream velocities and inlet orientations. Uniformity of deposits of 10 microm aerodynamic diameter particles on collection filters was examined for a sampling rate of 57 L min(-1), a sampler orientation of 90 degrees into the wind and wind speeds of 0.3-2 m s(-1). The coefficients of variation for the areal density of the deposits ranged from 6.1% to 37.2%. A miniature critical flow venturi with a constant sampling flow rate of 57 L min(-1) was developed for application to the new filter air sampler. It was demonstrated that the performance of the new filter air sampler is quite acceptable over a wide range of conditions. Overall the new filter air sampler design has been shown to provide enhanced performance with regard to sample handling, constant calibrated volumetric sample flow rate, and relatively unbiased sample aspiration performance compared with a traditional filter air sampler design.
Parulian
A
A
Department of Mechanical Engineering, Texas A&M University, College Station 77841, USA.
Rodgers
J C
JC
McFarland
A R
AR
D000336:Aerosols; D000398:Air Pollution, Radioactive / Q000032:analysis*; D004784:Environmental Monitoring / Q000295:instrumentation* / Q000379:methods; D004867:Equipment Design; D006801:Humans; D009688:Nuclear Reactors; D016273:Occupational Exposure; D014919:Wind
D000336:Aerosols