System for measuring moisture content

• US 4,165,633 A
• Filed: 02/09/1978
• Issued: 08/28/1979
• Est. Priority Date: 02/09/1978
• Status: Expired due to Term

• Current Assignee: Quintell of Ohio LLC
• Original Assignee: Motorola Process Control, Inc.
• Inventors: Raisanen, Walfred R.
• Primary Examiner(s): Ciarlante, Anthony V.
• Application Number:
  US05/876,300
• Time in Patent Office: 565 Days
• Field of Search: 73/76
• US Class Current: 73/76
• CPC Class Codes: G01G 19/00 Weighing apparatus or methods adapted for special purposes not provided for in the preceding groups electric measuring arrangements involving comparison with a reference value G01R17/00
• CPC Class Codes: G01G 19/40 with provisions for indicating, recording, or computing price or other quantities dependent on the weight indicating means for weighing apparatus G01G23/18; recording means for weighing apparatus G01G23/18; computers in general G06
• CPC Class Codes: G01G 19/414 using electronic computing means only
• CPC Class Codes: G01G 19/52 Weighing apparatus combined with other objects, e.g. furniture with walking sticks A45B3/08
• CPC Class Codes: G01G 23/3707 using a microprocessor
• CPC Class Codes: G01N 5/045 for determining moisture content

Abstract

A system for measuring moisture content in a porous material uses a microprocessor. The sample of material is placed on a load cell which provides an output to an analog-to-digital converter. The analog-to-digital converter provides a digital input for the microprocessor. The microprocessor is capable of providing an output indicative of the moisture content as a wet basis or a dry basis output. The system provides a highly accurate measurement of the moisture content while minimizing operator errors.

Claims

1. A gravimetric moisture measuring system, comprising:

means for weighing a material whose moisture content is to be determined, the means for weighing producing an output electrical signal representative of weight of the material;

an analog-to-digital converter coupled to the means for weighing to provide a digital output representative of the weight of the material;

a digital data processor for processing the digital output and for determining change of the digital output to allow the digital data processor to provide a continuously updated output representative of the moisture content of the material, the digital data processor including a microprocessor, a random access memory, and a read only memory;

means for displaying the output of the digital data processor; and

means for heating the material to cause a change in the moisture content of the material the means for heating being controlled by the digital data processor.

2. A gravimetric moisture measuring system as recited in claim 1 wherein the means for heating is controlled by the digital data processor, and the means for weighing is a load cell having a strain gauge means for determining weight of the material, and further including a multiplexer coupled to the analog-to-digital converter and having a plurality of reference voltages as inputs.

3. A gravimetric moisture measuring system as recited in claim 1 further including an amplifier coupled between the means for weighing and the analog-to-digital converter and wherein the digital data processor can provide a wet basis and a dry basis output to indicate the moisture content of the material.

4. A thermal gravimetric system for measuring moisture content of a porous material, comprising:

means for weighing the material, the means for weighing providing an output corresponding to weight of the material;

means for heating the material for a period of time to dry out moisture contained therein;

means to convert the output of the means for weighing from an analog signal to digital data;

means for processing the digital data in a manner to determine rate of change in the means for processing controlling the period of time the means for heating provides heat to the means to convert and having a plurality of reference voltages coupled to the multiplexer so that the reference voltages can be used for calibration and diagnostic purposes.

5. A thermal gravimetric system as recited in claim 4 wherein the means for weighing uses strain gauges to provide the output.

6. A thermal gravimetric system as recited in claim 5 wherein the means for heating is a nichrome heating element.

7. A thermal gravimetric system as recited in claim 6 wherein the means to convert comprises an amplifier, and an analog-to-digital converter.

8. A thermal gravimetric system as recited in claim 7 wherein the means for processing is a microprocessor and is also capable of controlling the means for heating and capable of providing an output when the material is over a predetermined weight, the means for processing further including a read only memory.

9. A thermal gravimetric system as recited in claim 4 wherein the means for processing can provide an output indicative of wet basis and dry basis moisture content of the porous material.

10. A thermal gravimetric system for measuring moisture content of a porous material, comprising:

a scale for measuring the material and for providing an electrical output corresponding to weight of the material;

a low bandwidth amplifier coupled to the scale to amplify the electrical output;

an analog-to-digital converter coupled to the amplifier for converting the amplified electrical output to a digital signal;

a microprocessor for processing the digital signal to provide outputs indicative of moisture content of the material;

a read only memory coupled to the microprocessor;

a digital data bus for coupling data to the microprocessor;

a peripheral interface adaptor coupled to the data bus for coupling a portion of data from the analog-to-digital converter to the microprocessor;

an alpha-numeric display coupled to the peripheral interface adaptor to display outputs of the microprocessor; and

a heating element to heat the material to dry out moisture contained therein, the heating element being coupled to the digital data bus so that the microprocessor can control how long a period of time the heating element provides heat.

11. The thermal gravimetric system of claim 10 wherein the moisture content of the material can be displayed as dry basis and wet basis.