The United States of America As Represented by the Administrator of the

The United States of America As Represented by the Environmental

John P Bell

A particle collector and fractionator having a 360.degree. omnidirectional gas inlet slit is disclosed herein. The collector and fractionator generally comprises a top and bottom fractionating member, each of which has a set of concentric, annular ring projections which are complementary to the other set. The ring projections form channels in the top and bottom members. The collector has at least one standoff for fastening together and spacing the top and bottom fractionating members. The concentric, annular ring projections form rectangular-shaped slits, when viewed in a cross-section. The slits, formed as they are by the ring-like projections, define a gas flow path from the omnidirectional gas inlet slit to a centrally disposed gas outlet port. Particles are collected and fractionated in the channel portions of the concentric, annular ring-like projections whenever particle laden gas flows into the gas flow path and out through the centrally disposed gas port. The minimum aerodynamic size of the particles collected and fractionated may be selected by adjusting the stand-offs so as to vary the cross-sectional area of the gas flow path, which in turn increases or decreases the velocity of a stream of particle laden gas flowing through the path. The cross-sectional areas may all be adjusted simultaneously by the use of the stand-offs.

High volume particle collector and fractionator

A particulate sample collector has a blower to draw air through ducting in which a filter collects particles. The blower is driven by a sealed inductive A.C. motor. A throttle in the ducting is controlled by a pneumatic motor in response to variation in pressure drop, to provide constant mass flow rate as the filter gradually becomes clogged.

Particulate sample collector

A particle collector and fractionator having a 360.degree., omnidirectional gas slit is disclosed herein. The collector and fractionator generally comprise a top and a bottom fractionating member, each of which has a set of concentric corrugations which are complementary to the other set. The collector also includes at least one spacer bracket for mounting and spacing the concentric corrugations of the top fractionating member over the concentric corrugations of the bottom member in complementary relationship, and forming an annular, concentrically corrugated gas flow path therebetween which is circumscribed by a 360.degree. gas slit. Particles are collected and fractionated in the valley portions of the concentric corrugations of the top and bottom members whenever particle laden gas flows from any direction into the concentrically corrugated gas flow path, and out through a centrally disposed gas withdrawal means in the bottom fractionating member. The minimum aerodynamic size of the particles collected and fractionated may be selected by adjusting the spacer brackets to vary the cross sectional area of the gas flow path, which in turn increases or decreases the velocity of a stream of particle laden gas flowing through the path.

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Raleigh, NC, United States of America

John P Bell