초록 ▼

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 s

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.

대표청구항 ▼

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 pas

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.