Re: Particulate Air Sampling

[Doug Turner <turners@earthlink.net>]

Larry, You need to look at Millipore brand filters and air samplers.  I
don't have their address, but the buyers guide of Nuclear News or the Thomas
guide will list them.  You don't mention the radioisotope, the chemical
form, the type of radioactivity (alpha, beta or gamma) or the anticipated
concentrations - information that would be make the responses more meaningful.

Millipore filters require a scintered backing plate for support and a lower
sampling flow rate than glass fiber filters and are ideal for alpha sampling.  

Doug Turner  Email:turners@earthlink.net

 and  At 08:56 PM 7/28/96 -0500, you wrote:
>Larry_R_Sanders_at_~BMI4@battelle.org wrote:
>> 
>> 
>>      I am currently faced with a need to perform air sampling for 0.1 - 0.3
>>      micron particulate radionuclides. I have information on how to perform
>>      this for 0.75 micron particles and higher. Below this range I have no
>>      information. I would appreciate any input I receive.
>> 
>>      Larry R. Sanders
>>      larry_r_sanders_at_~bmi4@battelle.org
>
>Larry and Fellow Radsafers,
>
>Particles at around 0.3 um diameter are generally the most difficult to
>filter.  They are too large to get much diffusional deposition by
>Brownian motion, and too small for much inertial deposition by impaction
>on the filter fibers.  (This is why absolute filters are tested at 0.3
>um particle diameter!)
>
>You can use a particulate filter (glass fiber or membrane) which has
>specs giving decent TRAPPING EFFICIENCY at 0.3 um.  Also, you need to
>check the linear air flow velocity thru your filter versus the
>manufacturer's specifications.
>
>If you are going to do alpha counting you need to determine the self
>absorption due to where the particulate deposits in the filter .... some
>filters deposit on the surface (membrane) and some deposit throughout
>the mass of the filter (paper, glass fiber).
>
>cheers, Wes.
>
>-- 
>Wesley R. Van Pelt, Ph.D., CIH, CHP                   KF2LG
>President, Van Pelt Assoc., Inc.            vanpelt@ios.com
>Consulting in radiological health and safety.
>"TIME, its what keeps everything from happening at once."
>
>