We use the dry dispersion unit and observe a second well defined peak of larger particles around 600-800 micron (there are not particles in that range). This happens also at higher pressure and it occurence seems to be random (sometime at the 1st measure, sometime at the 2nd/3rd, sometime in all measures). Intensity is not constant. Are there practical rules to minimize or avoid this effect with the dry dispersion unit?
Sandro Vidotto
This effect has been discussed in previous ResearchGate questions. For example:
https://www.researchgate.net/post/How_do_you_minimize_prevent_thermal_artefact_in_particle_size_determination_by_Malvern_Mastersizer_2000_and_3000_using_organic_dispersants
It is also mentioned in the international standard for laser diffraction, ISO13320:2009
It applies to wet as well as dry measurements and caused by excessive background fluctuation. Hints to avoid in:
PST & BDAS - An acronym approach to laser diffraction method development https://www.brainshark.com/malvern/vu?pi=zFhzA6idVz5chz0
Factors to be taken into account:
- Ensure that the supply gas (air) is free from moisture and oil. Check your filters
- Take measurements as groups of short measurements, 10 X 1 second measurement will ALWAYS be better than 1 X 10 second measurement
- Keep the overall measurement time short and ensure that all the material is measured within the filtered results
- Use the fine powder mode, if appropriate
- If measuring small material try and keep the obscuration higher (say ~ 3 - 4%) than normal to increase the signal
Send your .mmes raw data to me or your local Help Desk.
Sandro Vidotto
Your profile doesn't seem to (easily) show your location. Where are you based?
Hi Sandro Can you tell me a little about the outcome of your tests? Thank you.
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