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A condensation particle counter or CPC is a particle counter that detects and counts aerosol particles by first enlarging them by using the particles as nucleation centers to create droplets in a supersaturated gas. [2] Three techniques have been used to produce nucleation: Adiabatic expansion using an expansion chamber.
The light blocking optical particle counter method is typically useful for detecting and sizing particles greater than 1 micrometre in size and is based upon the amount of light a particle blocks when passing through the detection area of the particle counter. This type of technique allows high resolution and reliable measurement.
The SSA tends to unity if scattering dominates, with relatively little absorption, and decreases as absorption increases, becoming zero for infinite absorption. For example, the sea-salt aerosol has an SSA of 1, as a sea-salt particle only scatters, whereas soot has an SSA of 0.23, showing that it is a major atmospheric aerosol absorber.
Typically, they are measured (or counted) with condensation particle counters, which effectively enlarge the particles by condensing vapors onto them to make bigger and much more easily detectable droplets. [36] [37] The atomic composition of particulate samples can be measured with techniques such as X-ray spectrometry. [38]
Andersen's schematic for the six-stage Andersen sampler, detailing movement of air and hole sizes for the top two stages [1]. An Andersen sampler, Andersen impactor, or sieve impactor [2] is a cascade impactor used to determine the amount of viable pathogens in a given area, in particular bacteria and fungi.
The air now contains only particles of a certain diameter. The flow is introduced into a CPC, a condensation particle counter, which measures the concentration of particles in an aerosol sample. The CPC works by using butanol vapor condensation on the particles present in the air sample. The particles are exposed to butanol vapor heated to 39 °C.
Condensation is the change of the state of matter from the gas phase into the liquid phase, and is the reverse of vaporization. The word most often refers to the water cycle . [ 1 ] It can also be defined as the change in the state of water vapor to liquid water when in contact with a liquid or solid surface or cloud condensation nuclei within ...
Cascade impactors are strictly measurement-related devices. In addition to measuring the range of substances moved through an opening by aerosol, the impactor can also be used to determine the particle size of the distributed substance. A cascade impactor collects its samples in a graduated manner.