RE: Physical particle size to AMAD

["Tsurikov, Nick" <nick.tsurikov@ILUKA.COM>]

Dear Michael,



I would suggest that you use an impactor instead of the typical 25-mm or

37-mm dust sampling head.  Then you can analyse each stage (out of nine

usually) in either simple counter or a spectrometer (depending on what you

need).  After you've got the counts, quite tiresome calculation follows...

but then you have both AMAD and MMAD very easily.  From the experience I can

say that it is unlikely that you will be able to say what AMAD would be on

the basis of a physical particle diameter, - that is - unless you have heaps

of samples to 'get' the trend.

Anyway, if you will decide to use impactor, I have it all (both sampler

assembly instructions and calculations) written down for alpha-emitters

right here - please let me know if you will need it.



Kind regards

Nick Tsurikov

Eneabba, Western Australia

http://eneabba.net/ <http://eneabba.net/>  





		-----Original Message-----

		From:	Philippe Duport [mailto:pduport@uottawa.ca]

		Sent:	Friday, 15 June 2001 3:20

		To:	Michael Ford; radsafe@list.vanderbilt.edu

		Subject:	Re: Physical particle size to AMAD



		I do not think there is a safe way to derive the AMAD from

electron

		microscope images.  The AMAD is what it says it is: the

''AERODYNAMIC MEDIAN

		ACTIVITY diameter''.  You would have to know first if the

particle measured

		with the electron microscope is radioactive.  Then, the

aerodynamic diameter

		is the diameter of a sphere of density one with the same

settling velocity

		or mean Brownian motion velocity than the particle in your

cloud of

		particles.  Density and shape factors have a strong

influence on the AMAD.

		Further, in order to determine the M of the AMAD, you need

to know the size

		distribution of the particles of interest and to determine

the median of the

		distribution.    From electron microscope images, you can

only determine the

		median of the distribution.  You would have to use diffusion

batteries of

		the appropriate type for the size range of interest and

radiation counting

		to determine the AMAD.



		Philippe Duport



		----- Original Message -----

		From: "Michael Ford" <MFORD@PANTEX.COM>

		To: <radsafe@list.vanderbilt.edu>

		Sent: Thursday, June 14, 2001 11:22 AM

		Subject: Physical particle size to AMAD





		> Dear colleagues,

		>

		> I am looking for a published reference describing the

methodology for

		converting a physical particle diameter - as determined via

a scanning

		electron microscope - to an activity median aerodynamic

diameter (AMAD).

		>

		> If you have any information, please reply directly to me.

I receive

		RADSAFE messages in digest mode and was hoping to get some

feedback before

		the end of the day.

		>

		> Thanks very much in advance for your help!

		> v/r

		> Michael

		> mford@pantex.com

		>

		>

		>

		>

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