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Gas alarm

  • US 5,764,150 A
  • Filed: 04/10/1996
  • Issued: 06/09/1998
  • Est. Priority Date: 04/10/1996
  • Status: Expired due to Fees
First Claim
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1. A gas detector comprising:

  • a carbon monoxide (CO) sensor for measuring an environmental CO concentration and providing a variable electrical output responsive thereto; and

    a processor responsive to samples of said electrical output for computing a carboxyhemoglobin (COHb) level of an individual as if exposed to the measured CO concentration and providing an output signal based on the COHb level computed, whereina computed COHb level is obtained with each measurement sample, said computed COHb level associated with a current measurement sample being based on a relationship between a previously computed COHb level associated with previously measured samples and an equilibrium COHb level corresponding to the environmental CO concentration of the current measurement sample,said computed COHb level associated with the current measurement sample is an incrementally higher level than the previously computed COHb level when the equilibrium COHb level corresponding to the current sample is higher than the previously computed COHb level; and

    said incrementally higher level being based on a rate of COHb level increase associated with the environmental CO concentration of a current measurement sample;

    orsaid computed COHb level associated with the current measurement sample is an incrementally lower level than the previously computed COHb level when the equilibrium COHb level corresponding to the current sample is lower than the previously computed COHb level; and

    said incrementally lower level being based on an exponential decrease in COHb level from the previously computed COHb level towards the equilibrium COHb level corresponding to the current measurement sample;

    orsaid computed COHb level associated with a current measurement sample equals the previously computed COHb level when the equilibrium COHb level of the current measurement sample equals the previously computed COHb level.

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