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Dirty filter indicator

  • US 6,320,513 B1
  • Filed: 09/11/2000
  • Issued: 11/20/2001
  • Est. Priority Date: 09/11/2000
  • Status: Expired due to Fees
First Claim
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1. A dirty filter indicator device and an air filter combination comprising:

  • an air filter for a furnace or an air conditioning unit; and

    a one-piece whistle device having a restricted longitudinal cavity with an upper hollow circular flange, a cylindrical tubular body portion, and a truncated cone shaped nozzle portion consisting of a corrugated surface decreasing in radius and adapted to securely remain in the air filter under an airflow, the corrugated nozzle portion can be shortened to adjust the airflow tolerance of the whistle;

    whereby the whistle emits a warning sound by the increased airflow through the restricted cavity when the air filter becomes overloaded with dirt and dust.

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