US 11,280,750 B2Granted

Boiling point water activity measurement

AssigneeMETER Group, Inc. USA

InventorsAlex T. Mumford, Gaylon S. Campbell

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Abstract

Water activity measurement systems and methods for determining water activity of material samples in a test environment under controlled temperature and pressure conditions. The gas pressure in a test chamber is reduced or held constant while sample temperature is simultaneously tracked. The water activity of the sample can be determined by detecting the boiling point of the sample, at reduced pressure, over time, and calculating water activity using the atmospheric pressure and the saturation vapor pressure at the boiling temperature. The boiling point can be determined by observing an inflection point in the sample temperature over time, and the pressure and temperature at the onset of boiling can be determined at an intersection of trend lines extending from substantially linear intervals of temperature recordings over time.

Claims16

Dependent claims

A method of manufacturing a water activity sensor, the method comprising:

positioning a temperature sensor in a sealed chamber;
connecting a gas pressure sensor to the sealed chamber to measure an internal gas pressure of the sealed chamber;
connecting a gas evacuating device to the sealed chamber;
and
connecting a computing device to the temperature sensor and to the gas pressure sensor, wherein the computing device is configured to:
determine a temperature of a material sample using the temperature sensor;
determine the internal gas pressure of the sealed chamber using the gas pressure sensor;
detect onset of boiling in the material sample;
and
calculate a water activity of the material sample based on the temperature of the material sample at the onset of boiling and based on the internal gas pressure at the onset of boiling;
wherein detecting the onset of boiling in the material sample comprises adjusting over time at least one of the internal gas pressure and the temperature;
wherein detecting the onset of boiling in the material sample comprises determining an intersection point of at least two trend lines in a series of points falling on a plot of at least one of:
the temperature measured over time, and
the internal gas pressure versus the temperature.

11 more elements

Dependencies are inferred from the claim text.

Facts

Application: 16/678,155Filed 8 Nov 2019
Published: US 2021/0140903 A113 May 2021
Granted: 22 Mar 2022
Term ends: Not estimatedThe source records don’t support an estimate.

Classification4 codes

G01N 25/10
Of boiling point: analysis by measuring change of boiling point
G01D 21/02
Measuring or testing not otherwise provided for: measuring two or more variables by means not covered by a single other subclass
G01N
Investigating or analysing materials by determining their chemical or physical properties
G01D
Measuring not specially adapted for a specific variable