An equation for determining the distance that a suspended dust particle in the gas (taken as air) needs to settle has been obtained as a function of height of the chamber, velocity of the air, and diameter of the dust particle.This traveling distance by a particle with certain diameter also represents the maximum length of the chamber which the same particle will settle in, particles with larger diameters will settle out of the chamber, whereas particles with smaller diameters will settle in the chamber.The chamber, here, was assumed to be an infinite length chamber without walls to li