US PATENT SUBCLASS 131 / 212.2
.~.~.~.~.~.~ Concentric ducts

Current as of: June, 1999
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131 /   HD   TOBACCO

329  DF  TOBACCO USERS' APPLIANCE {8}
330  DF  .~ Device used for smoking {21}
200  DF  .~.~ Smoke treating {1}
201  DF  .~.~.~ Material separator and trap {7}
211  DF  .~.~.~.~ Chamber enclosed tubes or nipples {1}
212.1  DF  .~.~.~.~.~ Smoke direction changing {1}
212.2.~.~.~.~.~.~ Concentric ducts

DEFINITION

Classification: 131/212.2

Concentric dusts:

(under subclass 212.1) Subject matter wherein one or more tubes are inserted in a trap chamber and arranged such that there is one common axis of symmetry for causing fluid cross-flow of smoke along the pathways formed thereby (i.e., alternate directions of flow along adjacent concentric pathways).