The schematic of a condensation particle counter, operated by diffusional thermal cooling. Drawn according to the description at http://www.cas.manchester.ac.uk/restools/instruments/aerosol/cpc/. Notation: 1 – air inlet; 2 – porous material block, which is heated to saturator temperature, 3 – working fluid in reservoir, 4 – condenser, 5 – focusing nozzle, 6 – laser-based counter, 7 – air pump, 8 – air exhaust.Equipment used for area sampling of airborne nanomaterials.[1] The instruments shown here include a condensation particle counter, aerosol photometer, and two air sampling pumps for filter-based analysis.
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. This was the original technique used by John Aitken in 1888.[3]
Thermal diffusion.
Mixing of hot and cold gases.[2]
The most usually used (also the most efficient) method is cooling by thermal diffusion. Most abundantly used working fluid is n-butanol; during last years water is also encountered in this use.[4]
Condensation particle counters are able to detect particles with dimensions from 2 nm and larger. This is of special importance because particles sized down from 50 nm are generally undetectable with conventional optical techniques. Usually the supersaturation is ca. 100…200 % in condensation chamber, despite the fact that heterogeneous nucleation (droplet growth on surface of a suspended solid particle) can occur at supersaturation as small as 1%. The greater vapour content is needed because, according to surface science laws, the vapour pressure over a convex surface is less than over a plane, thus greater content of vapor in air is required to meet actual supersaturation criteria. This amount grows (vapor pressure decreases) along with decrease in particle size, the critical diameter for which condensation can occur at the present saturation level is called Kelvin diameter. The supersaturation level must, however, be small enough to prevent homogeneous nucleation (when liquid molecules collide so often that they form clusters – stable enough to ensure further growth is possible), which will produce false counts. This usually starts at ca. 300% supersaturation.[4]
On the right, a diffusional thermal cooling CPC is shown in operation. In order to ensure a high vapour content, the working liquid is in contact with a hollow block of porous material that is heated. Then the humified air enters the cooler where nucleation occur. Temperature difference between the heater and the cooler determines the supersaturation, which in its turn determines the minimal size of particles that will be detected (the greater the difference, the smaller particles get counted). As proper nucleation conditions occur in the center of the flow, sometimes incoming flow is divided: most of it undergoes filtering and forms the sheath flow, which the rest of flow, still containing particles, is inserted into via a capillary. The more uniform is obtained supersaturation, the sharper is particle minimal size cutoff. During the heterogeneous nucleation process in the nucleation chamber, particles grow up to 10…12 μm large and so are conveniently detected by usual techniques, such as laser nephelometry (measurement of light pulses scattered by the grown-up particles).[4]
^"General Safe Practices for Working with Engineered Nanomaterials in Research Laboratories". U.S. National Institute for Occupational Safety and Health: 29–30. May 2012. doi:10.26616/NIOSHPUB2012147. Retrieved 2017-03-05.
^ abAerosol Measurement: Principles, Techniques, and Applications, edited by Pramod Kulkarni, Paul A. Baron, Klaus Willeke, p384, [1] retrieved 15 May 2012
^Kulkarni, Baronand and Willeke, p381
^ abcCondensation Particle Counters (CPC)
and 26 Related for: Condensation particle counter information
only particles of a certain diameter. The flow is introduced into a CPC, a condensationparticlecounter, which measures the concentration of particles in...
A particlecounter is used for monitoring and diagnosing particle contamination within specific clean media, including air, water and chemicals. Particle...
morphology. Airborne UFPs can be measured using a condensationparticlecounter, in which particles are mixed with alcohol vapor and then cooled, allowing...
particles per unit volume of air (particle number concentration). This can be done by using a condensationparticlecounter (CPC). To measure the atomic composition...
Passing particles of the selected mobility to a detector such as a condensationparticlecounter allows the number concentration of particles with the...
particles (bosons) and predicted that they would condense into their lowest quantum state at low enough temperatures; this Bose–Einstein condensation...
ultrafine particles (PM0.1, less than 0.1 μm in diameter). Particle number can be measured with equipment such as condensationparticlecounters. Urban air...
was found that under certain conditions a fast-moving charged particle caused a condensation of supersaturated water vapor along its path. In 1911, Charles...
nanoparticle or ultrafine particle is a particle of matter 1 to 100 nanometres (nm) in diameter. The term is sometimes used for larger particles, up to 500 nm,[citation...
micrometer (or less) particles generally requires high-energy devices such as venturi scrubbers or augmented devices such as condensation scrubbers. Additionally...
and particulates, instruments include aerosol photometers and condensationparticlecounters. Handheld electronic monitors give instantaneous readouts, but...
Physics Communications, a scientific journal Condensationparticlecounter, instrument to count aerosol particles Amstrad CPC, a home computer of the 1980s...
In materials science and biology, capillary condensation is the "process by which multilayer adsorption from the vapor [phase] into a porous medium proceeds...
of non-volatile residue particles. A measurement device called a condensationparticlecounter then counts the residue particles to give a reading in parts...
properties, including microscopy and spectroscopy methods as well as particlecounters. Metrology standards and reference materials for nanotechnology, while...
conspiracy theory /ˈkɛmtreɪl/ is the erroneous belief that long-lasting condensation trails left in the sky by high-flying aircraft are actually "chemtrails"...
smaller particles, or may be too large or difficult to ship to a workplace.: 57 : 23–33 Suitable particlecounters can detect a wide range of particle sizes...
other molecules. Usually, DNA condensation is defined as "the collapse of extended DNA chains into compact, orderly particles containing only one or a few...
or high shear mixing). Condensation of small dissolved molecules into larger colloidal particles by precipitation, condensation, or redox reactions. Such...
spectrometer (SASS) uses a condensationparticlecounter (CPC) downstream of an AAC to measure high resolution aerodynamic particle size distributions (APSD)...
This is due to the fact that these particles can act as nucleation sites for mostly condensation and form particles near the MPPS. HEPA filters are designed...
In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls from clouds due to gravitational pull. The main...
types of condensation: Homogeneous condensation, as during a formation of fog. Condensation in direct contact with subcooled liquid. Condensation on direct...
Global Information
