US 2022/0026332 A1 · PULSED CONDENSATION PARTICLE COUNTER

Abstract

A method and apparatus to create water vapor supersaturation and particulate counts from an air sample. The method and apparatus include introducing an air sample into a chamber by passing a flow into the chamber through the inlet by pumping at the outlet. The method further includes closing the inlet while continuing the pumping to exhaust the air sample from the chamber through the outlet. The pumping is performed at a rate operable to reduce pressure inside the chamber such that the air sample in the central portion of the chamber cools, and water vapor from walls of the chamber has time to diffuse into the air sample in the chamber from the walls. The cycles are repeated by continuously repeating the introducing and closing. The walls of the chamber may be wet or dry.

Claims21

Dependent claims

A method for measuring a concentration of particles in air, comprising

introducing an air sample into a particle chamber through an inlet;
closing the inlet to isolate the particle chamber;
exhausting the air sample in the isolated particle chamber through a nozzle connected to an optical detector, said exhausting of the flow performed at a flow rate chosen to cause an expansion of any of the air sample inside the particle chamber, reduce a temperature of the any of the air sample inside the particle chamber, increase a relative humidity of any of the air sample inside the particle chamber, and cause vapor to condense on particles suspended in the any of the air sample inside the particle chamber, thereby forming droplets;
counting the droplets in the air sample as it is exhausted through the optical detector;
measuring a pressure from which an amount of air exiting the chamber can be assessed;
and
determining a particle concentration as a ratio of a number of droplets detected to the amount of air that has exited the chamber based on the counting and the measuring.

4 more elements

Dependencies are inferred from the claim text.

Pulsed condensation particle counter

Life of this patent

Pulsed condensation particle counter

Life of this patent

Abstract

Claims21