초록 ▼

A passive source infrared gas detector which uses an ambient temperature source and the space between the detector assembly and the source as the sample chamber is provided, the gas detector includes an infrared detector assembly for producing a first output, a second output, and a third output, the

A passive source infrared gas detector which uses an ambient temperature source and the space between the detector assembly and the source as the sample chamber is provided, the gas detector includes an infrared detector assembly for producing a first output, a second output, and a third output, the first output being indicative of the radiation received by the detector assembly at a first non-neutral spectral band which is absorbable by a preselected gas to be detected, the second output being indicative of the radiation received by the detector assembly at a first neutral spectral band from the passive infrared source, and the third output being indicative of the radiation received by the detector assembly at a second neutral spectral band from the passive infrared source. Signal processing means are included for manipulating the three outputs to determine the concentration of the gas being monitored. By adding additional detectors to the detector assembly which can detect radiation at spectral bands characteristic of additional gases, the infrared gas detector can be used to monitor the concentration of a plurality of gases.

대표청구항 ▼

A passive source infrared gas detector, comprising: a. an infrared detector assembly comprising i. a port for receiving radiation therethrough from the passive infrared source, ii. a first sensor, a second sensor, and a third sensor disposed to receive radiation through the port for producing a firs

A passive source infrared gas detector, comprising: a. an infrared detector assembly comprising i. a port for receiving radiation therethrough from the passive infrared source, ii. a first sensor, a second sensor, and a third sensor disposed to receive radiation through the port for producing a first output, a second output, and a third output indicative of the radiation incident on the first sensor, second sensor, and third sensor, respectively, iii. a first narrow band pass filter interposed between the port and the first sensor, the first narrow band bass filter producing an output therefrom indicative of the radiation incident on the first band pass filter at a first non-neutral spectral band which is absorbable by a preselected gas to be detected, iv. a second narrow band pass filter interposed between the port and the second sensor, the second narrow band pass filter producing an output therefrom indicative of the radiation incident on the second band pass filter at a first neutral spectral band, and v. a third narrow band pass filter interposed between the port and the third sensor, the third narrow band pass filter producing an output therefrom indicative of the radiation incident on the third band pass filter at a second neutral spectral band, b. temperature measuring means for producing an output corresponding to the ambient temperature of the first, second, and third sensors; c. signal processing means adapted to receive the outputs from the first sensor, second sensor, third sensor, and temperature measuring means and for sampling and at least temporarily storing the outputs of the first sensor, second sensor, third sensor, and temperature measuring means at preset intervals, the signal processing means including means for i. correcting the stored outputs of the first sensor, second sensor, and third sensor to compensate for the ambient temperature of the first sensor, second sensor, and third sensor, respectively, at the time of sampling, ii. calculating the temperature of the passive infrared source at the time of sampling based on the ratio of the corrected values of the outputs from the second and third sensors, iii. calculating a predicted output for at least one of the second or third sensors based on the calculated temperature of the passive infrared source for the sampling period, iv. calculating an attenuation factor by comparing the predicted output of at least one of the second or third sensors with the corrected output from the corresponding sensor for the sampling period, v. correcting the stored output of the first sensor by the attenuation factor, vi. determining the concentration of the gas for the sampling period from the corrected output from the first sensor, and vii. monitoring the concentration of gas based on a predetermined function and providing an output signal based on the monitoring.