US PATENT SUBCLASS 181 / 224-- .~.~ Sound absorbing ventilating duct or curb (e.g., a/c, heat, air flow type)

US PATENT SUBCLASS 181 / 224
.~.~ Sound absorbing ventilating duct or curb (e.g., a/c, heat, air flow type)

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}
224		.~.~ Sound absorbing ventilating duct or curb (e.g., a/c, heat, air flow type)

DEFINITION

Classification: 181/224

Sound absorbing ventilating duct or curb (e.g., A/C, heat, air flow type):

(under subclass 212) Subject matter comprising ducts or conduits for the movement of streams of air therethrough.

(1) Note. The ducts of this subclass type are usually lined with sound absorbing material or other sound absorbing structure for attenuating the sound waves of moving air.

SEE OR SEARCH CLASS

454, Ventilation,

262, for an air mixing building inlet airway having specific noise prohibiting structure; cross-reference art collection 906 for ventilating means, in general, including specific noise prohibiting structure; and subclasses 329, 338, and 341+ for inlet or outlet air pumps which forcefully admit or exhaust air from the stationary structure of a building.