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Method of filtering air through an air passageway

  • US 6,923,911 B1
  • Filed: 05/27/2003
  • Issued: 08/02/2005
  • Est. Priority Date: 10/20/1993
  • Status: Expired due to Term
First Claim
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1. The method of filtering air passing through an air discharge passageway, comprising the steps of:

  • removably positioning a pre-filter in the air discharge passageway;

    removably positioning a second filter in the air discharge passageway downstream of said pre-filter;

    removing said pre-filter from said air discharge passageway upon said pre-filter becoming clogged with material in the air passing therethrough; and

    passing air through said second filter.

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