Abstract The presence or concentration of a constituent in a gas is determined by cyclically compressing the gas to pressure modulate a beam of infrared energy that is directed through the gas as it is being repeatedly compressed. The resulting pressure modulated beam is passed through a narrow band interference filter onto a photocell which provides a fluctuating signal when the absorption characteristics of the gaseous constituent are within the filter''s selected narrow bandwidth. The fluctuating signal is amplified, rectified and then delivered to a direct current ammeter. Since the fluctuating signal is produced only when the gaseous constituent is present having the specific wavelength for which the filter has been selected, any ammeter reading indicates the presence of such a constituent; on the other hand, the amount of ammeter reading is indicative of the quantity of such gaseous constituent in the mixture.
APPARATUS FOR DETECTING THE PRESENCE OF A GAS COMPRISING AN ABSORPTON CELL FOR CONTAINING AT LEAST A PORTION OF SAID GAS MEANS FOR PRESSURE MODULATING THE GAS CONTAINED IN SAID CELL, A SOURCE OF INFRATED ENERGY AT ONE SAID CELL, A PHOTOCELL AT THE OTHER END OF SAID ABSORPTION CELL FOR PROVIDING A FLUTUATING SIGNAL IN ACCORDANCE WITH THE DEGREE SAID INFRARED ENERGY IS MOSULATED BY SAID PRESSURE MODULATING MEANS WHEN SAID GAS IS CAPABLE OF ABSORBING SOME OF SAID INFRARED ENERGY, AN INTERFERENCE FILTER BETWEEN SAID ABSORPTION CELL AND SAID PHOTOCELL FOR TRANSMITTING INFRARED ENERGY IN A NARROW BAND CONTAINING THE WAVELENGTH AT WHICH SAID GAS IS CAPABLE OF ABSORBING INFRARED ENERGY, A METERING DEVICE, OUT A VENTURI DEVICE CONNECTED BETWEEN SAID MELTNG DEVICE AND SAID ABSORPTION CELL.
Claim 2
Dependent Claim
129 words
APPARATUS FOR DETECTING THE PRESENCE OF A GAS COMPRISING AN ABSORPTON CELL FOR CONTAINING AT LEAST A PORTION OF SAID GAS MEANS FOR PRESSURE MODULATING THE GAS CONTAINED IN SAID CELL, A SOURCE OF INFRATED ENERGY AT ONE SAID CELL, A PHOTOCELL AT THE OTHER END OF SAID ABSORPTION CELL FOR PROVIDING A FLUTUATING SIGNAL IN ACCORDANCE WITH THE DEGREE SAID INFRARED ENERGY IS MOSULATED BY SAID PRESSURE MODULATING MEANS WHEN SAID GAS IS CAPABLE OF ABSORBING SOME OF SAID INFRARED ENERGY, AN INTERFERENCE FILTER BETWEEN SAID ABSORPTION CELL AND SAID PHOTOCELL FOR TRANSMITTING INFRARED ENERGY IN A NARROW BAND CONTAINING THE WAVELENGTH AT WHICH SAID GAS IS CAPABLE OF ABSORBING INFRARED ENERGY, A METERING DEVICE, OUT A VENTURI DEVICE CONNECTED BETWEEN SAID MELTNG DEVICE AND SAID ABSORPTION CELL.
Claim 3
Dependent Claim
43 words
The apparatus of claim 1 in which said Venturi device includes first and second tapered passages and a constricted throat therebetween, said first passage and saiD throat being connected to said metering device and said second passage being connected to said absorption cell.
Claim 4
Dependent Claim
14 words
The apparatus of claim 2 in which said pressure modulating means includes a bellows.