Distortion of cascade impactor measured size distribution due to bounce and blow-off
Accurate measurement of particle size distribution by a cascade impactor requires that particles remain on the collection surfaces after impaction. Recent studies show that, when a solid aerosol is sampled, significant rebound and re-entrainment of particles occur in cascade impactors. A mathematical model of a cascade impactor including collection efficiency functions for solid aerosols on various impaction surfaces was developed and used to operate upon a series of log-normal size distributions. The impactor modeled was a six stage Andersen operated at 28.3 L/min. When bare metal or glass impaction surfaces are used, the impactor indicates non-log-normal distributions and the estimated distribution parameters are in error by as much as a factor of 7. When glass fiber impaction surfaces are used, although less serious errors are indicated, the deviation from log-normality is significant for aerosols with MMD larger than 3 ..mu..m. When oil covered impaction stages are used the indicated distribution parameters are acceptably close to the input parameters. The accuracy of the model was verified experimentally.
- Research Organization:
- Univ. of Pittsburgh, PA
- OSTI ID:
- 5239581
- Journal Information:
- Am. Ind. Hyg. Assoc. J.; (United States), Journal Name: Am. Ind. Hyg. Assoc. J.; (United States) Vol. 41:6; ISSN AIHAA
- Country of Publication:
- United States
- Language:
- English
Similar Records
Calibration of Andersen nonviable impactor under special conditions of high flow and membrane filter surface coating
Particle bounce in a personal cascade impactor: a field evaluation
Related Subjects
Atmospheric-- Chemicals Monitoring & Transport-- (-1989)
54 ENVIRONMENTAL SCIENCES
ACCURACY
AEROSOL MONITORING
AEROSOLS
BLOWOFF
CASCADE IMPACTORS
COLLOIDS
DATA
DATA FORMS
DISPERSIONS
DISTRIBUTION
EQUIPMENT
ERRORS
EXPERIMENTAL DATA
FILTRATION
GRAPHS
INFORMATION
MASS
MATHEMATICAL MODELS
MONITORING
NUMERICAL DATA
PARTICLE SIZE
PARTICLE SIZE CLASSIFIERS
PARTICLES
SEPARATION PROCESSES
SIZE
SOLIDS
SOLS
TABLES