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Self-contained breathing apparatus

  • US 4,640,277 A
  • Filed: 05/17/1984
  • Issued: 02/03/1987
  • Est. Priority Date: 05/17/1984
  • Status: Expired due to Fees
First Claim
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1. A portable, self-contained breathing device of the type which may be used by industry and firefighters to protect a user from toxic atmospheric conditions, comprising:

  • a facepiece which can be worn on the face of a user to isolate the breathing functions of said user from ambient atmosphere;

    a supply of pressurized breathing air to be supplied to said facepiece in response to the inhalation demand of said user;

    air flow regulator means between said facepiece and said supply, said regulator means including a first air flow path and second air flow path, said first air flow path including first means to permit air passage from said supply to said facepiece in response to facepiece pressure decreases below a first preselected level, said second air flow path including second means which permits additional air passage from said supply to said facepiece in response to facepiece pressure decreases below a second preselected level lower than said first preselected level; and

    an electrical power supply;

    said first air passage means comprising;

    a first valve member,and means hydraulically responsive to changes in pressure in said facepiece caused by the breathing functions of said user to control the opening and closing of said first valve member; and

    said second air passage means comprising;

    a second valve member,pressure-sensitive means responsive to pressure changes in said facepiece, andmeans for opening said second valve member in response to a signal from said pressure sensitive means that facepiece pressure has decreased below said second preselected level;

    wherein said first air flow path is capable of of comfortably providing said user with the volume of breathing air required by said user during light to moderate physical exertion, andsaid pressure sensitive means is electrically connected to said electrical power supply to generate an electrical signal when said facepiece pressure has decreased below said preselected level.

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