Back to results
US 4,220,857 AGranted
Optical flame and explosion detection system and method
AssigneeSystron Donner Corporation
InventorClark I. Bright
Life of this patent
Estimating the term…
Loading patent…
Loading patent…
AssigneeSystron Donner Corporation
InventorClark I. Bright
Estimating the term…
Optical flame and explosion detection system having first and second channels with each of the channels being responsive to different combustion products and detecting radiation from the combustion products and converting the radiation into electrical signals. A filter is provided in each of the channels to limit the spectral response to a narrow band. The levels of the radiation are ascertained by level detectors which provide first and second signals when predetermined signal levels are reached in the first and second channels. A ratio of the two electrical signals from the first and second channels is ascertained. When a predetermined level is reached from the ratio of the electrical signals and also for the individual signals, an output signal is produced which can be utilized in actuating alarms and other devices.
In an optical detection system, first channel means responsive to radiation associated with a molecule, free radical or other combustion product whereby detected radiation is converted into a first electrical signal, second channel means responsive to radiation associated with a molecule, free radical or other combustion product which has a wavelength which differs from that of the wavelength of the combustion product sensed by the first channel whereby detected radiation is converted into a second electrical signal, first and second level comparators for ascertaining when the first and second electrical signals produced by the first and second channels rise above predetermined values, means for comparing the first and second electrical signals and ascertaining when they are substantially different from that given by a continuum radiation source and providing a third electrical signal and means for combining the outputs from the first and second level comparators and the third electrical signal and supplying an output signal when signals are supplied by the first and second level comparators and a signal is supplied by the means for comparing the first and second signals.
A system as in clain 1 wherein said first and second channels include narrow band filters for limiting the spectral response of each channel.
In a method for detecting a flame, selecting first and second wavelengths from a fire expected to be encountered one of which has far more radiation than would be encountered under normal Planckian radiation at that wavelength and temperature, detecting the radiation in those at least two wavelengths, providing first and second electrical signals corresponding thereto, combining the first and second electrical signals to ascertain whether the first and second signals as combined produce a third electrical signal which is actually different from that given by a continuum radiation source as defined by Planck's law, ascertaining when the first electrical signal exceeds a predetermined value to provide a fourth electrical signal, ascertaining when the second electrical signal exceeds a predetermined value and providing a fifth electrical signal and combining the third, fourth and fifth electrical signals to provide an output only when all three of said third, fourth and fifth signals are present.
In a method for detecting a flame, selecting at least three wavelengths expected to be encountered from a fire at least one of which has far more radiation than would be encountered with normal Planckian radiation at that wavelength and temperature, detecting the radiation at those at least three wavelengths, providing first electrical signals corresponding thereto, combining these signals in pairs to ascertain whether each two signals as combined produce second electrical signals which are actually different from that given by a continuum radiation source, as defined by Planck's Law, for some temperature range, ascertaining which of these second electrical signals must be further combined to produce a third electrical signal only when these second electrical signals exceed their individual predetermined values, ascertaining when the first electrical signals exceed their individual predetermined values to provide fourth electrical signals, and combining the third and fourth electrical signals to provide an output only when both of said third and fourth signals are present.
In an optical detection system, first channel means responsive to radiation associated with a molecule, free radical or other combustion product whereby detected radiation is converted into a first electrical signal, second channel means responsive to radiation associated with a molecule, free radical or other combustion product which has a wavelength which differs from that of the wavelength of the combustion product sensed by the first channel whereby detected radiation is converted into a second electrical signal, third channel means responsive to radiation associated with a molecule, free radical or other combustion product which has a wavelength which differs from that of the wavelengths of the combustion products sensed by either the first or second channel whereby detected radiation is converted into a third electrical signal, first, second and third level comparators for ascertaining when the first, second and third electrical signals produced by the first, second and third channels rise above predetermined values, means for comparing pairs of these first, second and third electrical signals and ascertaining when a pair as combined is substantially different from that given by a continuum radiation source and providing fourth electrical signals when they exceed individual predetermined values with the outputs from the first, second and third level comparators and supplying an output signal when signals are supplied by the first, second and third level comparator and a signal is supplied by the means for comparing the fourth electrical signal.
Dependencies are inferred from the claim text.