Sampler of gas borne particles
US3938367A · kind A · utility
Inventors
Key dates
| Filing date | Mar 28, 1975 |
| Grant date | Feb 17, 1976 |
| Priority date | — |
| Expiry date | Mar 28, 1995 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2001/2223
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An atmosphere sampler includes a very thin filter element with straight-through holes on the order of 1.mu.. A sample of air with particles to be examined is driven by means of a pressurized low molecular weight gas, e.g., He to the filter element front side. A partial vacuum may be present at the back side of the filter element. The pressure differential across the filter element is just below the rupture point of the filter element. By admixing a low molecular weight gas as the carrier gas with the air sampler the velocity with which the air sample is driven to the filter element is maximized for the particular pressure differential across the filter element, so that at least some particles with diameters less than the hole diameter do not follow changes in the air stream line direction as it passes through the filter element holes and therefore the smaller diameter particles are deposited on the filter element. When using a filter element of plastic material of a thickness on the order of 10.mu., a stainless steel back-up plate and a diffusion member are used to support the filter element when subjected to a pressure differential on the order of a few hundred atmospheres.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.