US PATENT SUBCLASS 181 / 258
.~.~.~ Pervious material interposed in flow path

Current as of: June, 1999
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181 /   HD   ACOUSTICS

175  DF  SOUND-MODIFYING MEANS {12}
212  DF  .~ Muffler, fluid conducting type {25}
256  DF  .~.~ With sound absorbing material {2}
258.~.~.~ Pervious material interposed in flow path

DEFINITION

Classification: 181/258

Pervious material interposed in flow path:

(under subclass 256) Subject matter wherein the sound absorbing material is directly in the flow path of the moving fluid, and the fluid must pass through the material to its exit.