How to select a mechanical filter using PM figures

[Tunalover]

Folks-
I need to control the incoming (dry ) air provided to cool a hydrogen fuel cell and the cleanliness of the air is stated as follows:
Fine particles (PM 2.5)<20 micrograms/cubic-meter
Coarse particles (PM 10)<50 micrograms/cubic-meter.
where PM stands for Particulate Matter and the 2.5 and 10 refer to the aerodynamic diameters of the particles in microns.

I passed this reqt on to an air filter mfgr and they didn't know what to make of it. Can anyone out there provide some direction on this? If a major air filter mfgr can't figure it out how am I supposed to? I appreciate all inputs!
Thanks!


I called an air filter company and they didn't know what to make of this.




Tunalover

 

[btrueblood]

Ugh. To convert from an aerodynamic diameter to a true diameter, you'd have to know the density of the material (or range of densities, or a probability distribution of density), and then make assumptions about the shape of the particles so that you could estimate the drag coefficient (Cd) and back-calculate a (real) particle diameter.

I would just assume the "aero diameter" is equal to the true particle diameter and go from there; but would also make that assumption very clear to the end user.

 

[sreid]

I would start looking for HEPA filters that will work with your air flow requirements.

http://en.wikipedia.org/wiki/Hepa