Carbon granule probe microphone for leak detection
Abstract
A microphone which is not subject to corrosion is provided by employing carbon granules to sense sound waves. The granules are packed into a ceramic tube and no diaphragm is used. A pair of electrodes is located in the tube adjacent the carbon granules and are coupled to a sensing circuit. Sound waves cause pressure changes on the carbon granules which results in a change in resistance in the electrical path between the electrodes. This change in resistance is detected by the sensing circuit. The microphone is suitable for use as a leak detection probe in recovery boilers, where it provides reliable operation without corrosion problems associated with conventional microphones.
- Publication:
-
National Aeronautics and Space Administration Report
- Pub Date:
- February 1985
- Bibcode:
- 1985nasa.reptR....P
- Keywords:
-
- Boilers;
- Carbon;
- Corrosion Resistance;
- Granular Materials;
- Leakage;
- Microphones;
- Ceramics;
- Circuits;
- Electrodes;
- Patents;
- Pipes (Tubes);
- Pressure Gradients;
- Instrumentation and Photography