Fire detector
AssigneeEngelhard Sensor Technologies, Inc.
InventorJacob Y. Wong
Life of this patent
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Abstract
A fire detector with a maximum average response time of less than 1.5 minutes is obtained by combining a smoke detector with a CO.sub.2 detector that uses NDIR sensor technology. The smoke detector is used to detect smoldering fires and to help prevent false alarms attributable to the CO.sub.2 detector. The CO.sub.2 detector is used to rapidly detect fires by measuring the rate of change of CO.sub.2 concentration. A signal processor generates an alarm signal when a smoldering fire is detected or alarm logic indicates that a fire has been detected.
Claims28
A fire detector, comprising:
- a smoke detector that generates a smoke detector output signal representative of light obscuration;
- a carbon dioxide ("CO.sub.2 ") detector that generates an output signal representative of CO.sub.2 concentration;
- and
- a signal processor which receives the smoke detector output signal and the CO.sub.2 detector output signal and generates an alarm signal when either of the following criteria is met:
- light obscuration exceeds a smoldering fire detection level for greater than a preselected time;
- or
- light obscuration exceeds a reduced threshold level and the rate of increase in the concentration of CO.sub.2 exceeds a first predetermined rate.
A fire detector, comprising:
- a smoke detector that generates a smoke detector output signal representative of light obscuration;
- a ("CO.sub.2 ") detector that generates an output signal representative of CO.sub.2 concentration;
- and
- a signal processor which receives the smoke detector output signal and the CO.sub.2 detector output signal and generates an alarm signal when either of the following criteria is met:
- light obscuration exceeds a reduced threshold level and the rate of increase in the concentration of CO.sub.2 exceeds a first predetermined rate;
- or
- the rate of increase in the concentration of CO.sub.2 exceeds a second predetermined rate.
A fire detection logic system, comprising:
- a first logic path for determining if a first input signal representative of light obscuration exceeeds a smoldering detection level for greater than a preselected time;
- a second logic path for determining the rate of increase in the concentration of carbon dioxide ("CO.sub.2 ") from a second input signal representative of the rate of change of CO.sub.2 concentration;
- and
- a logic device for generating an alarm signal when either of the following criteria is met:
- light obscuration exceeds the smoldering fire detection level for greater than the preselected time;
- or
- light obscuration exceeds the reduced threshold level and the rate of increase in the concentration of CO.sub.2 exceeds the first predetermined rate.
Dependencies are inferred from the claim text.