Device for Measuring The Activity of a Liquid in a Complex Medium and Associated Method

• US 20120266663A1
• Filed: 11/04/2010
• Published: 10/25/2012
• Est. Priority Date: 11/04/2009
• Status: Active Grant

• Current Assignee: Centre National De La Recherche Scientifique, Universite Montpellier II
• Original Assignee: Centre National De La Recherche Scientifique, Université Montpellier 2 Sciences Et Techniques
• Inventors: Benet, Jean-Claude, Cousin, Bruno, Cherblanc, Fabien, Ouoba, Samuel
• Granted Patent: US 9,316,572 B2
• Time in Patent Office: Days
• US Class Current: 73/64.45
• CPC Class Codes: G01N 2203/0085 Compressibility
• CPC Class Codes: G01N 3/08 by applying steady tensile or compressive forces G01N3/28 takes precedence
• CPC Class Codes: G01N 7/14 by allowing the material to emit a gas or vapour, e.g. water vapour, and measuring a pressure or volume difference determining urea G01N33/48742

Abstract

A device for measuring the activity of a liquid in a complex medium and an associated method, the device comprising a sealed enclosure in which the complex medium is intended to be placed and means for maintaining this enclosure at a constant temperature T, characterized in that it comprises: a means (14) for modifying the total volume of the enclosure; a pressure sensor (22) for measuring the total pressure in the enclosure; and means (24) for calculating the activity of the liquid in the complex medium from the temperature T, from the total volume of the enclosure and from the total pressure in the enclosure.

Claims

1. A device for measuring the activity of a liquid in a complex medium, comprising a sealed enclosure in which the complex medium is intended to be placed and means for maintaining this enclosure at a constant temperature T, wherein the device comprises:

a means for modifying the total volume of the enclosure;

a pressure sensor for measuring the total pressure in the enclosure;

a means for calculating the activity of the liquid in the complex medium, from the temperature T, the total volume of the enclosure and the total pressure in the enclosure.

2. The device for measuring the activity of a liquid in a complex medium as claimed in claim 1, in which the means for modifying the total volume of the enclosure is a piston which can be displaced to modify this volume, one face of said piston forming a wall of the enclosure.

3. The device for measuring the activity of a liquid in a complex medium as claimed in claim 2, in which the enclosure is formed by a cylinder sealed at one of its ends by a sample-holder and, at its other end, by said face of the piston.

4. The device for measuring the activity of a liquid in a complex medium as claimed in claim 3, in which the cylinder is mounted on rods, which are in turn mounted on a baseplate of the device.

5. The device for measuring the activity of a liquid in a complex medium as claimed in claim 4, in which the sample-holder is mounted on a base, which is in turn mounted on the baseplate.

6. The device for measuring the activity of a liquid in a complex medium as claimed in claim 3, in which means are provided to displace the piston in the cylinder, for example of screw/nut type.

7. The device for measuring the activity of a liquid in a complex medium as claimed in claim 3, in which a graduated drum is provided to identify the position of the piston in the cylindrical tube.

8. The device for measuring the activity of a liquid in a complex medium as claimed in claim 3, in which a sump is provided, arranged inside the sample-holder.

9. A method for measuring the activity of a liquid in a complex medium, wherein the method comprises the steps consisting, after having placed the complex medium in a sealed enclosure, temperature isotherm T, in:

(a) performing a basic increment Av_j of the enclosure volume;

(b) after having reached the thermodynamic balance between the complex medium and the enclosure, maintaining the total pressure p_i, measured in the enclosure;

(c) determining a relationship (R1) between the total pressure p_i, the partial liquid vapor pressure at balance p_veq and the partial pressure of the ideal gas not being dissolved, for example air, the latter being expressed using the ideal gas law, such that the relationship (R1) is expressed;

10. The method for measuring the activity of a liquid in a complex medium as claimed in claim 9, in which the step (d) consists in repeating the steps (a) to (c) at least 5 times.