| 摘要 |
<p>A membrane filter furnishes dust samples readily classified by size into respirable and non-respirable fractions. The dust laden air impinges centrally on the membrane and a springy support reflects the particles. The air flow, now radial, transports the particles outward the further, the greater their rebound height, i.e. the greater the particle size. Respirable fractions of under 5 mu size are thus deposited within a certain radius from the centre.</p> |
