Current as of: June, 1999
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Internet Version by PATENTEC © 1999      Terms of Use


413  DF  .~> Ash pan
*  DD  .~> Boiler circuit {1}
*  DD  .~> Circulatioon {1}
417  DF  .~> Drip plate in boiler
*  DD  .~> Fire-engine boiler {1}
420  DF  .~> Furnace gases
421  DF  .~> Offtake flue
422  DF  .~> Furnace gases and steam
*  DD  .~> Horizontal fire tube boiler {2}
428  DF  .~> Internal conduit {5}
434  DF  .~> Locomotive tender
435  DF  .~> Pan in steam space {1}
437  DF  .~> Safety valve
438  DF  .~> Spray to steam space
439  DF  .~> Stack
441  DF  .~> Steam {1}
444  DF  .~> Water tube boiler


Classification: 122/412

(under the class definition) Subject matter comprising means for preheating water being fed to a boiler or principal heater.

(1) Note. In order that devices for heating feed water shall be classified in any of the boiler subclasses they must be so intimately connected and combined with the boiler structure that they are inseparable therefrom or not of general application for heating water and not excluded therefrom by the main definition of this class. Devices for heating water that may be used for boiler purposes or for any other purposes, are not classified in this class.


1, and 3, for combinations of feed heaters with other elements that form a boiler plant.

20, for structure of devices for heating water that could readily be applied for heating feed water (this is a very closely related subclass).

36, for boilers having means for heating the water by steam jets or tubes before the boiler is fired up. 37, for closures of boilers having separate compartments, one compartment being used for impure water full of mud or salt, the steam passing to the other compartment which contains purified water, and feed heaters.

40+, for flash boilers having a preheater for the water intimately associated with the flash boiler.

62, 63 and 65, for heating water introduced into the heaters in the firebox.

68+, and 196, for boilers provided with heating tubes through which the boiler water circulates and is heated, but when the feed water is being fed to the boiler the boiler circulation is stopped by means of automatically operated valves and the feed water is heated in the tubes before it is conducted to the main part of the boiler.

82, for horizontal fire tube boilers with superposed feed water heaters in open communication with the boiler, delivering water to the bottom of the boiler from the feed heater.

83, and 123, for horizontal fire tube and vertical fire tube boilers, respectively, that have transverse diaphragms, the feed water entering the compartment farthest from the firebox and being progressively heated as it approaches the firebox.

89, for water arches at the rear of horizontal fire tube boilers that serve as feed water heaters.

106, for horizontal fire tube boilers having water walls that may be used as a feed water heater.

118, and 159, for special types.

125, for similar structure for feed heaters.

151, for horizontal flue boilers having return fire tubes, with a smokebox closure having a separate comparment that may serve as a feed water heater.

189, 190, 193+, and 202, for boilers where water is introduced into a certain part of the structure before passing to the main part of the boiler.

192, for water bridge walls and drums where water is introduced and heated.

195+, for means for heating feed water when it is introduced (these are really main boiler structures with means for incidentally heating the water when it is introduced before it enters the horizontal cylinder).

371+, for water grates (water grates used as feed water heaters will be found in the various types of boilers having water grates; a complete list of boilers with water grates is given in the "search notes" to subclass 371).

379+, for feed water heaters combined with boiler cleaning devices, traps, and filters.

396, for combined cleaning and feed water heating system where the blow-off water is used to heat the feed water when refilling the boiler (especially used for cleaning and filling locomotive boilers).

398, for boilers having a circulating conduit provided with a sediment trap or filter, the water being introduced into the circulating conduit.

403, for feed heaters having a sediment trap (compare also subclasses 91 and 202).

457, and 458, for gravity boiler feeders with incidental feed water heater.

477, for combination of a water tube boiler with a steam superheater and a feed water heater.

494, for surrounding casings to prevent radiation of heat from a boiler which heats feed water.

497, for feed heating furnace and boiler front. 498, for water-cooled doors for heating feed water.

499, and 500, for furnace mouths or fuel door openings provided with water heaters and used for heating feed water.


60, Power Plants, appropriate subclasses for feed water heaters in power plants.

165, Heat Exchange, appropriate subclasses for a heat exchanger, per se, even though disclosed as a feed water heater.

210, Liquid Purification or Separation,

175+, for a heater or heat exchanger combined with a separator, and subclasses 198.1+ for a separator with means

to add treating material, e.g., steam.

261, Gas and Liquid Contact Apparatus, appropriate subclasses for apparatus that contact a liquid with a gas not limited to heat exchange but which may be disclosed as a feed water heater.