US PATENT SUBCLASS 122 / 439
.~ Stack

Current as of: June, 1999
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122 /   HD   LIQUID HEATERS AND VAPORIZERS

412  DF  FEED HEATERS {17}
439.~ Stack

DEFINITION

Classification: 122/439

(under subclass 412) Subject matter wherein the feed water heater either forms part of a stack or is located in a smokestack.

SEE OR SEARCH THIS CLASS, SUBCLASS:

20, for water heaters of general application located in the smokestack or chimney.

123, and 440, for stack feed water heaters heated by both furnace gases and steam.