Back to results
US 4,350,507 AGranted
Respirable particle sampling instruments
AssigneeNational Research Development Corporation
InventorsGeorge K. Greenough, Richard C. Brown
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
AssigneeNational Research Development Corporation
InventorsGeorge K. Greenough, Richard C. Brown
Estimating the term…
A respirable particle sampling instrument passes air with a fan through a passage having first a pre-filter thereacross to collect non-respirable airborne particles and then a main filter to collect respirable particles, the pre-filter being formed by a random fibrous network having interstices of such size and distribution as to capture a major proportion of the non-respirable particles within a prescribed range of velocity for which particle capture is predominantly by inertial impaction. The pre-filter suitably comprises porous foamed plastics material, preferably in a structure of contiguous layers having successively changing pore sizes and distribution, preferably of a polyester, and preferably having an oil coating. The pre-filter will normally have a penetration function approximating the so-called Johannesburg curve.
A respirable particle sampling instrument comprising a housing defining an air passageway therethrough, an electric fan mounted in said passageway to draw and pass air into and through said passageway, a main filter located across said passageway to collect respirable particles borne by said air passing therethrough, and a pre-filter located across said passageway upstream of said main filter to collect non-respirable particles borne by said air passing therethrough, said pre-filter being formed by a random fibrous network having interstices of such size and distribution as to capture a major proportion of the non-respirable airborne particles in an air flow therethrough within a prescribed range of velocity for which particle capture is predominantly by intertial impaction.
Dependencies are inferred from the claim text.