METHOD AND APPARATUS FOR MEASURING THE MOISTURE CONTENT OF WOOD

• US 3,807,055 A
• Filed: 04/23/1973
• Issued: 04/30/1974
• Est. Priority Date: 04/23/1973
• Status: Expired due to Term

• Current Assignee: Gerald S. Kraxberger
• Original Assignee: Gerald S. Kraxberger
• Inventors: Kraxberger, Gerald S.
• Primary Examiner(s): Camby, John J.
• Application Number:
  US05/353,497
• Time in Patent Office: 372 Days
• Field of Search: 34/9.5,13.4,13.8,16.5,46 73/336.5
• US Class Current: 34/402
• CPC Class Codes: F26B 2210/16 Wood, e.g. lumber, timber
• CPC Class Codes: F26B 25/22 Controlling the drying process in dependence on liquid content of solid materials or objects
• CPC Class Codes: G01N 27/048 for determining moisture content of the material
• CPC Class Codes: G01N 33/46 Wood

Abstract

A method apparatus for determining the moisture content of wood by measurement of the impedance of the wood utilizing an alternating current electrode sensor connected to a shielded conductor with the shield being ungrounded and driven in phase with the conductor.

Claims

1. A method of measuring the moisture content of wood comprising:

providing a moisture-measuring site;

positioning wood at the measuring site;

positioning in proximity to the wood an electrode sensor having a shielded conductor connected to a source of alternating current;

driving the shielded conductor and the conductor shield in phase to form a circuit including the wood; and

measuring the impedance in the circuit across the measuring site.

2. The method of claim 1 wherein said measuring site is in a wood-drying kiln.

3. The method of claim 1 wherein multiple electrode sensors each having a shielded conductor with the conductor and shield driven in phase are used to sense the moisture content of the wood.

4. The method of claim 3 wherein the shielded conductors are electrically connected to an averaging circuit means to average the impedance measurements of the multiple sensors.

5. A system for measuring the moisture content of wood comprising:

a source of alternating current;

an electrode sensor and conductor means connecting said sensor to said source of alternating current;

said conductor means including a conductor lead extending from said sensor toward said source;

an electrically conductive shield in surrounding relationship to said lead; and

shield driver means between said lead and said source for driving said shield in phase with said source.

6. A system according to claim 5 wherein said shield driver means includes a shield driver circuit having a shield driver amplifier means.

7. A system according to claim 5 wherein there are multiple electrode sensors, each having a said conductor lead, conductor shield and shield driving means, the said leads being electrically connected to an averaging circuit means between said leads and said impedance measuring means for averaging the impedance sensed by said electrode sensors.

8. A system according to claim 5 including means defining an automatic trip circuit means electrically connected to an impedance indicating means and operable upon measurement of a predetermined low moisture condition to signal said condition.

9. A system according to claim 8 wherein said automatic trip circuit means includes time delay means operable upon the energizing of said trip circuit means to delay the signalling of said predetermined low moisture condiTion until after said condition has persisted for a preset period of time.