ELECTROLYTIC ALCOHOL DETECTION

• US 3,838,971 A
• Filed: 05/04/1973
• Issued: 10/01/1974
• Est. Priority Date: 05/04/1973
• Status: Expired due to Term

• Current Assignee: Alcohol Countermeasure Systems Corp.
• Original Assignee: Clarence E. Albertson
• Inventors: Albertson, Clarence E.
• Primary Examiner(s): Serwin, R. E.
• Application Number:
  US05/357,155
• Time in Patent Office: 515 Days
• Field of Search: 23/23B,232E,254E,255E 128/2C 204/195B 324/71
• US Class Current: 436/132
• CPC Class Codes: G01N 27/4045 for gases other than oxygen
• CPC Class Codes: G01N 33/4972 Determining alcohol content for vehicle safety devices B60K28/06
• CPC Class Codes: Y10S 436/90 Breath testing
• CPC Class Codes: Y10T 436/204165 Ethanol

Abstract

An electrolytic cell is formed of a pair of lead electrodes and an aqueous solution of sulfuric acid or phosphoric acid. The electrolyte is subjected to an environment comprising a gas such as human breath to be tested for the presence or concentration of alcoholic vapor. The electrical conductivity of the cell is measured and compared to its conductivity when subjected to ambient air or a gas containing a predetermined concentration of alcoholic vapor.

Claims

1. A METHOD OF DETECTING THE PRESENCE OF ALCOHOLIC VAPOR IN A GAS, USING AN ELECTROLYTIC CELL WHICH INCLUDES A PAIR OF ELECTRODES FORMED OF LEAD, AND AN ELECTROLYTE COMPRISING AN AQUEOUS SOLUTION OF AN ACID SELECTED FROM THE GROUP CONSISTING OF SULFURIC ACID AND PHOPHORIC ACID, THE METHOD COMPRISING THE STEPS OF SUBJECTING AND ELECTROLYTE TO AN ENVIROMENT COMPRISING A CONTROL GAS FREE OF ALCOHOLIC VAPOR, MEASURING THE ELECTRIC CAL CONDUCTIVITY OF THE ELECTROLYTIC CELL, REPLACING THE CONTROL

2. A method of determining the presence and concentration of alcoholic vapor in a gas, using an electrolytic cell which includes a pair of electrodes formed of lead, and an electrolyte comprising an aqueous solution of an acid selected from the group consisting of sulfuric acid and phosphoric acid, the method comprising the steps of subjecting the electrolyte to an environment comprising a first control gas free of alcoholic vapor, effecting a first measurement of the electrical conductivity of the electrolytic cell, replacing the first control gas with a second control gas having a predetermined concentration of alcoholic vapor, effecting a second measurement of the electrical conductivity of the electrolytic cell, replacing the second control gas with the first control gas, adjusting the conductivity of the electrolylic cell to a value approximately equal to the value indicated by the first measurement, replacing the first control gas with a gas having an unknown concentration of alcoholic vapor if any, effecting a third measurement of the electrical conductivity of the electrolytic cell, and comparing the second and third measurements.

3. The method as defined in claim 2, wherein each of the measurements of electrical conductivity is carried out by applying an electric potential of predetermined constant magnitude to the electrodes, and determining the magnitude of the electric current flowing through the cell.

4. The method as defined in claim 3 wherein the predetermined constant magnitude of the electric potential applied to the electrodes is in the range of 2.0 volts to 3.0 volts.

5. The method as defined in claim 2, wherein the electrolyte comprises a solution of approximately 40% by weight of sulfuric acid in water.

6. An electrolytic alcohol detection device comprising means forming a chamber for receiving control gases and gases to be tested for the presence of alcoholic vapor, the chamber having an inlet and an outlet, and means forming an electric circuit including an electrolytic cell disposed in the chamber, a source of constant dc, electric potential, means responsive to changes in electric current, and means electrically connecting the cell, the potential source and the current-responsive means in series, the electrolytic cell comprising a pair of electrodes each formed of lead, the electrodes being formed to hold by surface tension an electrolyte therebetween in a position to be in contact with a gas received in the chamber, the electrolyte comprising an aqueous solution of an acid selected from the group consisting of sulfuric acid and phosphoric acid.

7. An electrolytic alcohol detection device as defined in claim 6, wherein one of the electrodes comprises an annulus of a size to receive and hold a drop of the electrolyte, and the other electrode comprises a terminus positioned to be in electrical contact with the drop of electrolyte at a location spaced from and within the annulus.