Patent ID: 7415981

Claim:
A filter pad comprising: a first filter layer having a major surface and made of woven material; and a first flow distributor disposed adjacent said first filter layer and in a covering relation with less than the entire major surface of said first filter layer, said first flow distributor made of non-woven material that is substantially impermeable to gas flowing through the first filter layer; a second filter layer having a major surface and made of woven material adjacent to the first flow distributor in a position filtering gas flowing past the first flow distributor; a second flow distributor in a layer disposed adjacent said second filter layer in a covering relation with less than the entire major surface of said second flow distributor receiving gas flowing through the second filter layer, said second flow distributor made of non-woven material that is substantially impermeable to gas; and a third filter layer having a major surface and made of woven material disposed adjacent said second flow distributor layer in a position receiving and filtering flow therefrom.