Particle size measuring

T. Allen, "Particle Size Measurement , 2nd ed.. Chapman and Hall, London (1975). 

Some particle size measuring techniques ate more particle shape sensitive than others. Data obtained by different methods can be significantly different, and whenever a particle size is reported, the measuring technique and conditions should always be mentioned. Even using the same equipment, the extremes of the distributions (low and high 10%) are usually not readily reproducible. 

In particle-size measurement, gravity sedimentation at low soHds concentrations (<0.5% by vol) is used to determine particle-size distributions of equivalent Stokes diameters ia the range from 2 to 80 pm. Particle size is deduced from the height and time of fall usiag Stokes law, whereas the corresponding fractions are measured gravimetrically, by light, or by x-rays. Some commercial instmments measure particles coarser than 80 pm by sedimentation when Stokes law cannot be appHed. 

The terminal velocity in the case of fine particles is approached so quickly that in practical engineering calculations the settling is taken as a constant velocity motion and the acceleration period is neglected. Equation 7 can also be appHed to nonspherical particles if the particle size x is the equivalent Stokes diameter as deterrnined by sedimentation or elutriation methods of particle-size measurement. 

A wide variety of particle size measurement methods have evolved to meet the almost endless variabiUty of iadustrial needs. For iastance, distinct technologies are requited if in situ analysis is requited, as opposed to sampling and performing the measurement at a later time and/or in a different location. In certain cases, it is necessary to perform the measurement in real time, such as in an on-line appHcation when size information is used for process control (qv), and in other cases, analysis following the completion of the finished product is satisfactory. Some methods rapidly count and measure particles individually other methods measure numerous particles simultaneously. Some methods have been developed or adapted to measure the size distribution of dry or airborne particles, or particles dispersed inhquids. 

T. Alien. Particle Size Measurement. Chapman Hall, London (1990). 

Allen, T., 1996. Particle Size Measurement, 5th edition. London Chapman and Hall. 

A-6 Altitude and Atmospheric Pressures, 578 A-7 Vapor Pressure Curves, 579 A-8 Pressure Conversion Chart, 580 A-9 Vacuum Conversion, 581 A-10 Decimal and Millimeter Equivalents of Fractions, 582 A-11 Particle Size Measurement, 582 . A-12 Viscosity Conversions, 583 A-13 Viscosity Conversion, 584 A-14 Commercial Wrought Steel Pipe Data, 585 A-15 ... 

A-11 Particle Size Measurement, 434 A-l 2 Viscosity Conversions, 435 A-13 Viscosity Conversions, 436 A-14 Commercial Wrought Steel Pipe Data, 437 A-15 Stainless Steel Pipe Data, 440 A-16 Properties of Pipe, 441 A-17 Equation of Pipes, 450 A-l 8 Circumferences and Areas of Circles, 451 A-19 Capacities of Cylinders and Spheres,... 

PARTICLE SIZE MEASUREMENTS OF SOLID PROPELLANTS, EXPLOSIVES, AND PYROTECHNICS... 

For the particle size measurements of boron and barium dichromate, components of pyrotechnic delay compns, Freeman (Ref 46) evaluated the MSA. Particle Size Analyzer versus microscopy, gravitational liq sedimentation,... 

---