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Monitoring apparatus

  • US 7,963,692 B2
  • Filed: 02/26/2009
  • Issued: 06/21/2011
  • Est. Priority Date: 02/27/2008
  • Status: Active Grant
First Claim
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1. A monitoring apparatus for monitoring time by a color change indicator capable of being used multiple times, comprising:

  • a colored fluid which causes an observable color change in a transparent section of the apparatus during operation of the apparatus;

    a first reservoir holding at least a portion of the colored fluid; and

    a second reservoir, defined by non-porous surfaces, abutting the first reservoir;

    wherein the first reservoir is responsive to pressure on it such that a portion of the colored fluid flows into the second reservoir;

    wherein the second reservoir is responsive to a lack of pressure in the first reservoir such that a portion of the colored fluid in the second reservoir reverses flow back into the first reservoir once the first reservoir is not under pressure.

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