Measuring and testing – Gas analysis – Gas chromatography
Patent
1986-09-19
1988-04-12
Levy, Stewart J.
Measuring and testing
Gas analysis
Gas chromatography
422 84, 128730, G01N 114
Patent
active
047366192
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention pertains to a device to analyze the alcohol content of a gas, especially for testing an automobilist's alcoholemia level; more specifically, it pertains to an arrangement of testing circuits which allow it to be ensured that exhaled air is taken under satisfactory conditions of reliability and precision.
It is known that, in order to ensure the reliability of an alcoholemia test, the air sample which is analyzed must come from the deepest part of the lungs: the term "alveolar air" is commonly used to designate the fraction of air which is discharged at the end of a complete exhalation period because it comes from the alveolar passages of the lungs. It is the analysis of the alcohol content of this "alveolar air" which allows the driver's alcoholemia level to be determined with sufficient precision.
Various devices are known which are intended to measure the alcohol content of a gas. For example, U.S. Pat. No. 4,346,584 describes an automatic analyzing device which takes a sample of gas at the end of the exhalation as soon as the pressure decreases in the intake conduit. French Pat. No. 2,449,877 describes a device for taking a breath sample, comprising a pressure sensor which controls the activation of a timing unit which delays the instant at which the measurement is taken. Nonetheless, these known devices do not provide a reliable measurement of the alcohol content of alveolar air under all circumstances.
SUMMARY OF THE INVENTION
One of the goals of the invention is to propose a device which can measure the alcohol content of air which is discharged at the end of an exhalation period of a subject being tested.
Another purpose of the invention is to propose such a device which can take a predetermined quantity of alveolar air, at the end of the exhalation period, regardless of the subject's thoracic capacity.
Another purpose of the invention is to propose such a device endowed with means to verify that the subject is continuously and fully exhaling air from his lungs, especially without again inhaling fresh air.
In this spirit, the invention pertains essentially to a device to analyze the alcohol content of a gas, especially to test an individual's alcoholemia level; this device is different in that it comprises a conduit (11) for the circulation of said gas, a controlled pumping device (14), connected to said conduit to take a predetermined volume of said gas when it is activated, with this pumping device being connected to means to detect and measure alcohol (25) and means (17) to control the activation of the pumping device comprising a cascade assembly of a device (27) which is sensitive to the pressure prevailing in said conduit and a device (28) to evaluate a volume of gas, controlled by said pressure sensitive device.
With such an arrangement, it is ensured that the air which is analyzed is taken towards the end of the exhalation period.
According to another important characteristic of the invention, the device also comprises means to detect a low threshold of the pressure prevailing in said conduit and logical means to link the signal issued by said evaluation means and the signal issued by said low threshold detection means, to formulate the control for the pumping system. Thus, with such a device, the air to be analyzed is taken only when a minimum amount of air has been exhaled and when the subject stops blowing into the conduit, with the pressure in the latter falling at that time to a value close to atmospheric pressure.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will emerge more clearly in light of the description below of two possible embodiments for a device according to the principle thereof; with said description being provided on an example basis and given in reference to the attached drawing, in which:
FIG. 1 is a skeleton diagram of a first analyzing device according to the invention;
FIG. 2 is a skeleton diagram, analogous to that in FIG. 1, of a second device according to the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMB
REFERENCES:
patent: 3238783 (1966-03-01), Wright
patent: 3764270 (1973-10-01), Collier et al.
patent: 4132109 (1979-01-01), Vandersyde
patent: 4248245 (1981-02-01), Kempin
patent: 4297871 (1981-11-01), Wright et al.
patent: 4298010 (1981-11-01), Eckstein et al.
patent: 4346584 (1982-08-01), Boehringer
patent: 4535780 (1985-08-01), Gur et al.
patent: 8278636 (1981-07-01), Voigt et al.
Levy Stewart J.
Williams Hezron E.
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