Particle counts

For dust-control work, it is recommended that a preliminary quah-tative examination of the dust first be made without a detailed particle count. A visual estimate of particle-size distribution will often provide sufficient guidance for a preliminaiy assessment of reqmrements for collection eqmpment. 

Particle count the number of particles greater than 0.5 im in 1 ml of water (maximum particle size is 1 im). 

Particle count tests are important to anticipating potential system or machine problems. This is especially true in hydraulic systems. The particle count analysis made a part of a normal lube oil analysis is quite different from wear particle analysis. In this test, high particle counts indicate that machinery may be wearing abnormally or that failures may occur because of temporarily or permanently blocked orifices. No attempt is made to determine the wear patterns, size and other factors that would identify the failure mode within the machine. 

Let us suppose that we have a particle counting instrument which sorts and counts the number of particles at a given particle size. The experimental data that we collect are ... 

The tube can be a source of metal particles and must be cleaned carefully before sterilization. The USP contains a test procedure and limits the level of metal particles in ophthalmic ointments. The total number of metal particles detected under 30 x magnification that are 50 pm or larger in any dimension is counted. The requirements are met if the total number of such particles counted in 10 tubes is not more than 50 and if not more than one tube is found to contain more than 8 such particles. 

Two general methods have evolved. One uses a stirred tank system, while the other depends on the measurement of particle size or surface area change via particle counting or image analysis techniques. 

Because the reproducibility of a-particle counting with the Pylon sources was quite good, this study was conducted as follows. Four identical samples, i.e., same material, were placed in the decay product standard sources for a period of 24 h at a time. The four samples were then removed and measured. Gross a-particle count and a-spectrometry analysis of the samples were done. 

Material Gross a-particle Count R Qualitative Agreement with Previous Data Remarks... 

S.R. stands for spectral ratio, i.e., the a-particle count ratio between 212 Po and 212Bi. ... 

Tables II (radon progeny) and III (thoron progeny) present some of the data obtained. In these Tables Nj and N2, obtained with the weak reference sources, stand for the gross a-particle count measured 1-min and 40-min after exposure, respectively. The symbols N3 and N4 represent the same as Nj and N2, respectively, but for the strong references sources. Furthermore, in the above Tables Ni 2 = N1 +...

Ararwal, J.K. and G.J. Sem, Continuous Flow, Single-Particle-Counting Condensation Nuclei Counter, J. Aerosol Sci. 11 343-358 (1980). 

Special control measures will be required when the actual particle count (of the size range specified in the standards or by an industrial hygienist) exceeds 6.8 mppcf. 

Computer-assisted molecular modeling package, 10 331-333 Computer-assisted tomography (CAT), sodium iodide in, 22 827 Computer-automated image analysis, as a particle counting method, 18 146-149 Computer-controlled viscometers, 21 732 Computer controller, closed loop fuel metering system, 10 57 Computer control loop, components of, 20 677-678... 

Particle contamination, in ion implantation, 14 445-446 Particle counters, 13 466 18 139 Particle counting... 

Time of flight (TOF), 75 660-661 Time-of-flight (ToF) mass analyzers, 24 109 Time of flight diffraction (TOFD), 79 486 Time-of-flight instrumentation, in particle counting, 78 150—151 Time-of-flight-SIMS technique, 24 109 Time-resolved fluorimetry, 74 148-149 Time-resolved spectra, analysis of, 74 613 Time standards, 75 749—750 Time-temperature parameters (TTP), 73 471, 478, 479 creep properties and, 73 480 Time-temperature superposition, 27 746-747... 

The scattering models employed in data processing invariably involve the assumption of particle sphericity. Size data obtained from the analysis of suspensions of asymmetrical particles using laser diffraction tend to be somewhat more ambiguous than those obtained by electronic particle counting, where the solid volumes of the particles are detected. 

The origins, constituents, effects and possible benefits from the removal of dust in livestock buildings are given. Reductions in dust mass, airborne bacteria and particle counts of at least 50% were reported using a filter system in weaner pig houses. 

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