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Power assisted air-purifying respirators

  • US 4,430,995 A
  • Filed: 05/24/1982
  • Issued: 02/14/1984
  • Est. Priority Date: 05/29/1981
  • Status: Expired due to Term
First Claim
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1. An air-purifying device for attachment to a facepiece of the positive pressure type for providing purified air to the wearer of the facepiece, said air-purifying device comprising:

  • (a) electrically powered pump means for pumping air, said pump means including inlet means and outlet means;

    (b) means connecting said pump means to a source of electrical power and including means for varying the power supplied from said power source to said pump means;

    (c) means for removing contaminants in the air;

    (d) means connecting said contaminant removing means to said pump inlet;

    (e) means defining an expandable chamber having an inlet and an outlet;

    (f) means biasing said expandable chamber towards a collapsed condition for maintaining a positive pressure in said chamber;

    (g) means connecting said chamber inlet with said pump outlet;

    (h) means adapted to connect said chamber outlet to a facepiece;

    (i) sensing means for sensing the degree of expansion of said expandable chamber; and

    (j) means connecting said sensing means with said power varying means for varying the power supplied to said pump means in dependence on the state of expansion of said expandable chamber.

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