System and method for resonant filter mass monitoring
AssigneeTRC Companies, Inc.
InventorPedro Lilienfeld
Life of this patent
Estimating the term…
Abstract
A system and method for measuring particulate concentrations. The system includes a substantially planar, peripherally supported filter for capturing the particulates, an oscillator for oscillating the filter substantially perpendicular to its planar surface, and a sensor for measuring the frequency of oscillation.
Claims28
A system for detecting airborne particulate concentration, comprising:
- (a) a substantially planar filter;
- (b) an air sampler for obtaining an ambient air sample and causing said air sample to flow through said filter whereby airborne particulates in said air sample are deposited on said filter;
- (c) an oscillator for causing oscillatory movement of said filter substantially perpendicular to the plane of said filter;
- and
- (d) a detector for detecting said oscillatory movement of said filter.
A system for determining airborne particulate concentration, comprising:
- (a) a substantially planar filter;
- (b) an air sampler for obtaining an ambient air sample and causing said air sample to flow through said filter at a flow rate (Q) whereby airborne particulates in said air sample are deposited on said filter;
- (c) an oscillator for causing said filter to oscillate substantially perpendicular to the plane of said filter at a natural resonant frequency (f);
- (d) a detector for detecting said oscillatory movement of said filter;
- and
- (e) particulate concentration determining means for determining the airborne particulate concentration (C.sub.m) of said sample based on the ratio between the initial (f.sub.0) and final (f.sub.1) resonant frequencies of said filter.
A method for determining airborne particulate concentration, comprising the steps of:
- (a) obtaining an ambient air sample and providing said sample at a flow rate (Q);
- (b) collecting airborne particulates in said sample on a substantially planar filter;
- (c) oscillating said filter in a direction substantially perpendicular to the plane thereof;
- (d) detecting a natural resonant frequency (f) of said oscillating filter;
- and,
- (e) determining the airborne particulate concentration of said sample based on the ratio between initial (f.sub.0) and final (f.sub.1) resonant frequencies of said filter.
A system for determining airborne particulate concentration comprising a sampling chamber, a filter mounted within said chamber such that an air sample obtained by said chamber is passed through said filter and airborne particles in said sample are collected by said filter, an oscillator for oscillating said filter, and a detector for determining the concentration of particles collected by said filter, said system being characterized in that
- said filter includes a collection area on which said particles are collected, and
- said oscillator is arranged to oscillate substantially only the portion of said filter comprising said collection area.
Dependencies are inferred from the claim text.