US PATENT SUBCLASS 122 / 142
.~.~.~ Return fire tube

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

135.1  DF  FLUE {4}
136 R  DF  .~ Horizontal {7}
140.1  DF  .~.~ Internal water tube {7}
142.~.~.~ Return fire tube

DEFINITION

Classification: 122/142

(under subclass 140) Devices having return fire tubes, with some form of water tubes within the large flues.

SEE OR SEARCH THIS CLASS, SUBCLASS:

77, for analogous art.

147, for horizontal flue boilers having return fire tubes,

with transverse water tubes in the flues.

149+, for horizontal flue boilers with return fire tubes.