Elutriator is a device used for separating lighter particles from heavier ones using a vertically-directed stream of gas or liquid. The smaller or lighter particles rise to the top because their terminal velocities are lower than the velocity of the rising fluid. Basically an elutriator is a vertical settling chamber. It consists of one or more tubes or chambers arranged in series, into which a dust-laden gas stream passes upward at a velocity defined by the gas flow rate and the tube cross-sectional area. It retains or removes particles above a given size or size range and emits the remaining airborne particles. Large particles with terminal settling velocities greater than the upward gas velocity are separated and collected at the bottom of the chamber. Smaller particles with lower settling velocities are carried out of the collector. Changing the gas velocities will therefore affect the particle size collected.