Gas analysers of the selective radiation absorption type with a calibration cell
First Claim
1. A gas analyser of the selective radiation absorption type, comprising:
- at least one source of radiation;
a measurement chamber for receiving a gaseous mixture containing at least one gas whose concentration is to be measured, said measurement chamber being disposed in a measurement path to receive radiation from the source;
means for periodically interrupting the radiation entering said measurement path;
at least one detector sensitive to, and disposed to receive, radiation which has passed through the measurement chamber;
a calibration cell for cooperating with the said path, said cell enclosing a given concentration of the gas whose concentration is to be measured in a sealed enclosure; and
a flexible-wall chamber, forming part of said sealed enclosure, for controlling the pressure in the interior of said enclosure in accordance with the ambient temperature and pressure.
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Accused Products
Abstract
A gas analyser of the infra-red radiation absorption type, particularly for measuring the amounts of CO2 and CO in vehicle exhaust gases, comprises a pair of infra-red radiation sources arranged to direct their radiation along a measurement path and a reference path respectively, the radiation entering each path being periodically interrupted by a rotating commutator. Two measurement chambers for receiving the gas to be analysed and respective detection chambers for CO2 and CO are alternately disposed along the measurement path, while two reference chambers and two more such detection chambers are alternately disposed along the reference path, corresponding detection chambers being connected to respective differential pressure sensors of the variable capacitance type. The analyser includes a calibration cell containing predetermined concentrations of CO2 and CO. The cell is selectively interposable in the measurement path, and is connected to a flexible-wall chamber. The flexible-wall chamber defines with the cell a sealed enclosure, and serves to maintain the pressure within the sealed enclosure equal to ambient pressure.
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Citations
5 Claims
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1. A gas analyser of the selective radiation absorption type, comprising:
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at least one source of radiation; a measurement chamber for receiving a gaseous mixture containing at least one gas whose concentration is to be measured, said measurement chamber being disposed in a measurement path to receive radiation from the source; means for periodically interrupting the radiation entering said measurement path; at least one detector sensitive to, and disposed to receive, radiation which has passed through the measurement chamber; a calibration cell for cooperating with the said path, said cell enclosing a given concentration of the gas whose concentration is to be measured in a sealed enclosure; and a flexible-wall chamber, forming part of said sealed enclosure, for controlling the pressure in the interior of said enclosure in accordance with the ambient temperature and pressure. - View Dependent Claims (2, 3, 4, 5)
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Specification