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Filter change indicator

  • US 5,862,737 A
  • Filed: 04/10/1996
  • Issued: 01/26/1999
  • Est. Priority Date: 04/10/1996
  • Status: Expired due to Term
First Claim
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1. An air cleaning device comprising:

  • a housing defining an air inlet opening, an air outlet opening, and a first air flow path formed between the inlet and outlet openings;

    a blower disposed in the housing and arranged to move air in the first air flow path from the inlet to the outlet;

    a multiple speed motor rotatably coupled to the blower;

    a blower control for varying the operational mode of the motor;

    an air filter disposed within the housing in the first air flow path;

    a filter change indicator that is operable in various orientations of the air cleaning device, comprising;

    a tubulation disposed with the housing and having a first and a second end, the tubulation defines a hollow center which forms an inclined passage that extends between the first end and the second end, the first end is in fluid communication with a second air flow path formed between the first end and second end, wherein the second air flow path is open to atmospheric pressure, and the second end is in fluid communication with the first air flow path inside the housing at a location downstream of the filter;

    a step formed at the first end of the tubulation;

    a moveable visual indicator retained within the hollow center;

    a viewing window disposed on the housing above the second end of the tubulation; and

    an air flow metering system formed in the housing for regulating the air flow rate through the tubulation.

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