micro,macroscopic and particle sizing Flashcards
the diameter of a sphere having the same volume as the particle
dv = volume equivalent diameter
the diameter of a sphere having the same surface area as the particle
ds = surface equivalent diameter
the diameter of a sphere having the same projected area as the particle
dp = projected area equivalent diameter
the diameter of a sphere having the same density and free-fall velocity in a given fluid as the particle
dst = the stokes’ equivalent diameter
the diameter of a sphere that is just able to pass through the same sieve as the particle
da = sieve equivalent diameter
the diameter of a sphere with the same viscous drag as the particle in a given fluid at the same viscosity
dd = aerodynamic equivalent diameter
which ESD is important for a suspension ?
dst = the stokes’ equivalent diameter
relates to sedimentation rate
Which ESD is important for inhalation aerosol?
Aerodynamic diameter
why is it normally desirable to have a narrow PSD(particle size distribution)?
means that the size of the particles produced is almost uniform.
What happens if the particles have broad PSD?
may result in slow filtration rate, poor flowability and variable dissolution rate.
What are the types of diameter for particle size analysis?
Martin’s diameter: This is the length of the line which bisects the particle.
Feret’s diameter: this is the distance between the two tangents of the particle.
Projected perimeter diameter: this is the diameter of the circle having the same perimeter as that of the particle.
Projected area diameter: this is the diameter of the circle having the same area as that of the particle.
The following instrument can reliably measure the size of emulsion droplets with 0.01 micron diameter:
Select one:
Scanning electron microscope
Dynamic light scattering
Light microscope
Andreasen pipette
Dynamic light scattering
