Acoustic pycnometer

• US 4,072,046 A
• Filed: 09/03/1976
• Issued: 02/07/1978
• Est. Priority Date: 09/03/1976
• Status: Expired due to Term

• Current Assignee: The Dow Chemical Company (Dow, Inc.)
• Original Assignee: The Dow Chemical Company (Dow, Inc.)
• Inventors: Lao, Binneg Y.
• Primary Examiner(s): Gill, James J.
• Application Number:
  US05/720,480
• Time in Patent Office: 522 Days
• Field of Search: 73/67, 73/67.1, 73/69, 73/149, 73/299 B, 73/290 V, 73/67.2
• US Class Current: 73/574
• CPC Class Codes: G01N 29/11 by measuring attenuation of acoustic waves

Abstract

An improved pycnometer in which the sample whose volume to be measured is put in a closed chamber to which an electro-mechanical transducer is coupled. The transducer is excited at a constant frequency. The change in impedance of the transducer is then read as a function of the volume of the sample.

Claims

1. Pycnometer apparatus comprising an enclosable chamber for receiving a sample whose volume is to be measured, an electro-acoustical transducer coupled to the interior of said chamber, electronic signal generator means for electrically energizing said transducer at a predetermined frequency having a wave length at least four times the longest dimension of said chamber, electrical bridge circuit means coupled between said means for electrically energizing and said electro-mechanical transducer, said bridge circuit including means for nulling the signal across said bridge circuit when said chamber is empty, and means for reading the signal across said bridge when a sample is disposed in said chamber, the magnitude of said signal being a function of the volume of the sample.

2. Apparatus in accordance with claim 1, wherein said electro-mechanical transducer is a dynamic microphone or dynamic speaker.

3. Apparatus in accordance with claim 1, wherein said means for nulling said signal includes a variable inductance and variable resistance.

4. Apparatus in accordance with claim 1, wherein said chamber includes opening and closing means.