04574615 is referenced by 110 patents and cites 6 patents.

A method and apparatus for detecting the presence of a gaseous substance within a space bounded by an enclosure utilizes the fact that sound is not transmitted through a vacuum and is transmitted through the material of the enclosure. A sonic wave transmitter and a sonic wave receiver are engaged with the material of the enclosure and separated by the space. Using the calculated arrival times and/or amplitudes for the soundwave portions through the space and through the material of the enclosure, it can be determined whether a soundwave portion has passed through the space and thus a leakage of gaseous substance into the space above a threshold amount has taken place.

Title
Sonic apparatus and method for detecting the presence of a gaseous substance in a closed space
Application Number
6/562558
Publication Number
4574615
Application Date
December 19, 1983
Publication Date
March 11, 1986
Inventor
Charles W Hammond
Lancaster
OH, US
John R Bower
Lynchburg
VA, US
Agent
D Neil LaHaye
James C Simmons
Robert J Edwards
Assignee
The Babcock & Wilcox Company
LA, US
IPC
G01N 31/00
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