US 12,111,241 B2
Pulsed diffusion condensation particle counter
Susanne Vera Hering, Berkeley, CA (US); Gregory Stephen Lewis, Berkeley, CA (US); and Steven Russel Spielman, Oakland, CA (US)
Assigned to Aerosol Dynamics Inc., Berkeley, CA (US)
Filed by Aerosol Dynamics Inc., Berkeley, CA (US)
Filed on Jan. 5, 2022, as Appl. No. 17/568,940.
Application 17/568,940 is a continuation in part of application No. 17/492,955, filed on Oct. 4, 2021.
Application 17/492,955 is a continuation in part of application No. PCT/US2020/026641, filed on Apr. 3, 2020.
Claims priority of provisional application 62/830,346, filed on Apr. 5, 2019.
Prior Publication US 2022/0128445 A1, Apr. 28, 2022
Int. Cl. G01N 15/06 (2024.01); G01N 15/075 (2024.01)
CPC G01N 15/06 (2013.01) [G01N 15/075 (2024.01)] 20 Claims
OG exemplary drawing
 
1. A method for measuring a concentration of particles in air, comprising:
introducing an air sample into a particle chamber having walls that are wetted with a condensable fluid, and having one portion of the walls maintained at a temperature warmer than other portions of the walls;
passing air from the particle chamber through an optical detector in a steady mode by:
passing a constant flow of air through the particle chamber causing vapor of the condensable fluid to condense on particles suspended in the air, thereby forming droplets;
counting the droplets exiting the chamber and passing through the optical detector;
determining an amount of air passing through the particle chamber
determining a first particle concentration from a number of droplets exiting the chamber, and the amount of air that has exited the chamber during the counting; and
passing air from the particle chamber through an optical detector in an expansion mode by:
closing a chamber inlet and exhausting the air sample in the particle chamber at a rate chosen to cause an expansion of any of the air sample inside the particle chamber, reduce a temperature of the air sample inside the particle chamber, increase a level of vapor saturation of any of the air sample inside the particle chamber, and cause vapor to condense on particles suspended in 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;
determining of the amount of air passing through the particle chamber during the expansion mode; and
determining a second particle concentration as a ratio of a number of droplets exiting the chamber to the amount of air that has exited the chamber based on the counting and the measuring.