Particle size, how do you measure it?

[kaos1]

Greetings,

Being new to this, I have submitted a sample of a powder that we produce for particle size analysis.

Two methods were used: "Time of Flight" and Laser defraction. Each gave very different results. Time of Flight gave a nice standard bell curve and the Laser Defraction gave two distinct peaks. The means of these two different methods were substantially different also. Time of Flight indicated the population was MUCH smaller.

The range of particle sizes was from <0.1 to 400 microns when combining both methods.

Can anyone explain the difference between these two methods? Also, how can we be sure what the population really is?

Thanks,
Kaos1

 

[MortenA]

maybe you should try to calibrate your laser defrac. meter? Or try contacting the vendor with your problem.

Pure theoretically but: If you had particles with two different densities might it not be that a Time Of Flight under un-lucky circumstances would show one peak?

Best regards

Morten

 

[kaos1]

MortenA,

Thanks for your input. All equipment is in calibration and standards were run before testing the samples.

Another note: The powder is not comprised of a single entity but a blend of approx. 50 different chemicals.

Kaos1

 

[25362]

You may need fluidization, dispersion and de-agglomeration resulting from cohesive effects, prior to measuring particle size distribution.