F22D1/00	7	Feed-water heaters, i.e. economisers or like preheaters	F22D1/00	F22D1/00		696
F22D1/003	8	{Feed-water heater systems (F22D1/325, F22D1/36 and F22D1/40 take precedence)}	F22D1/00	F22D1/00		468
F22D1/006	8	{with heating tubes (F22D1/24 takes precedence)}	F22D1/00	F22D1/00		114
F22D1/02	8	with water tubes arranged in the boiler furnaces, fire tubes or flue ways	F22D1/02	F22D1/02		852
F22D1/04	9	the tubes having plain outer surfaces, e.g. in vertical arrangement	F22D1/04	F22D1/04		84
F22D1/06	10	in horizontal arrangement	F22D1/06	F22D1/06		132
F22D1/08	9	the tubes having fins, ribs, gills, corrugations, or the like on their outer surfaces, e.g. in vertical arrangement	F22D1/08	F22D1/08		63
F22D1/10	10	in horizontal arrangement	F22D1/10	F22D1/10		134
F22D1/12	9	Control devices, e.g. for regulating steam temperature	F22D1/12	F22D1/12		143
F22D1/14	9	Safety or venting devices	F22D1/14	F22D1/14		51
F22D1/16	8	with water tubes arranged otherwise than in the boiler furnace, fire tubes, or flue ways	F22D1/16	F22D1/16		209
F22D1/18	9	and heated indirectly	F22D1/18	F22D1/18		160
F22D1/20	9	and directly connected to boilers	F22D1/20	F22D1/20		85
F22D1/22	9	and provided for rotary movements	F22D1/22	F22D1/22		6
F22D1/24	8	with fire tubes or flue ways traversing feed-water vessels	F22D1/24	F22D1/24		106
F22D1/26	8	with means, other than tubes, to separate water and heating medium, e.g. bulk heaters without internal flues or tubes, jacketted smoke-boxes or flue or flues	F22D1/26	F22D1/26		64
F22D1/28	8	for direct heat transfer, e.g. by mixing water and steam	F22D1/28	F22D1/28		239
F22D1/30	9	with stages, steps, baffles, dishes, circular troughs, or other means to cause interrupted or cascading fall of water	F22D1/30	F22D1/30		74
F22D1/32	8	arranged to be heated by steam, e.g. bled from turbines	F22D1/32	F22D1/32		811
F22D1/325	9	{Schematic arrangements or control devices therefor}	F22D1/32	F22D1/32		275
F22D1/34	9	and returning condensate to boiler with main feed supply	F22D1/34	F22D1/34		105
F22D1/36	8	Water and air preheating systems	F22D1/36	F22D1/36		526
F22D1/38	9	Constructional features of water and air preheating systems	F22D1/38	F22D1/38		95
F22D1/40	8	Combinations of exhaust-steam and smoke-gas preheaters	F22D1/40	F22D1/40		43
F22D1/42	8	specially adapted for locomotives	F22D1/42	F22D1/42		852
F22D1/44	9	Smoke-gas preheaters	F22D1/44	F22D1/44		10
F22D1/46	9	Exhaust-steam preheaters	F22D1/46	F22D1/46		24
F22D1/48	9	Details	F22D1/48	F22D1/48		10
F22D1/50	8	incorporating thermal de-aeration of feed-water (de-aeration produced in the course of direct heat transfer F22D1/28)	F22D1/50	F22D1/50		1571
F22D3/00	7	Accumulators for preheated water	F22D3/00	F22D3/00		167
F22D3/02	8	arranged within combustion chambers	F22D3/02	F22D3/02		28
F22D3/04	8	combined with steam accumulators	F22D3/04	F22D3/04		99
F22D3/06	8	directly connected to boilers	F22D3/06	F22D3/06		76
F22D3/08	8	specially adapted for locomotives	F22D3/08	F22D3/08		15
F22D3/10	9	Control devices	F22D3/10	F22D3/10		22
F22D5/00	7	Controlling water feed or water level; Automatic water feeding or water-level regulators	F22D5/00	F22D5/00		346
F22D5/02	8	with an intermediate compartment from which the water is fed by gravity after mechanically moving the compartment, the movement being controlled according to water level	F22D5/02	F22D5/02		59
F22D5/04	8	with pivoting buckets	F22D5/04	F22D5/04		149
F22D5/06	8	with receptacles external to, but in free communication with, the boilers and adapted to move up and down in accordance with change in water level	F22D5/06	F22D5/06		58
F22D5/08	8	with float-actuated valves	F22D5/08	F22D5/08		223
F22D5/10	9	and with pistons or membranes unitary with the feed inlet valves	F22D5/10	F22D5/10		190
F22D5/12	9	and with dipping tubes	F22D5/12	F22D5/12		164
F22D5/14	8	responsive to thermal expansion and contraction, e.g. of solid elements	F22D5/14	F22D5/14		253
F22D5/16	9	of fluids	F22D5/16	F22D5/16		118
F22D5/18	8	for varying the speed or delivery pressure of feed pumps	F22D5/18	F22D5/18		181
F22D5/20	9	without floats	F22D5/20	F22D5/20		15
F22D5/22	9	with floats	F22D5/22	F22D5/22		136
F22D5/24	8	with electric switches	F22D5/24	F22D5/24		192
F22D5/26	8	Automatic feed-control systems	F22D5/26	F22D5/26		426
F22D5/28	9	responsive to amount of steam withdrawn; responsive to steam pressure	F22D5/28	F22D5/28		55
F22D5/30	9	responsive to both water level and amount of steam withdrawn or steam pressure	F22D5/30	F22D5/30		138
F22D5/32	9	influencing the speed or delivery pressure of the feed pumps	F22D5/32	F22D5/32		179
F22D5/34	9	Applications of valves	F22D5/34	F22D5/34		441
F22D5/36	9	for feeding a number of steam boilers designed for different ranges of temperature and pressure	F22D5/36	F22D5/36		28
F22D7/00	7	Auxiliary devices for promoting water circulation	F22D7/00	F22D7/00		293
F22D7/02	8	Saddles or like directing plates fitted to furnace tubes	F22D7/02	F22D7/02		90
F22D7/04	8	Injectors for water or steam	F22D7/04	F22D7/04		79
F22D7/06	8	Rotary devices, e.g. propellers	F22D7/06	F22D7/06		10
F22D7/08	9	Arrangements of pumps, e.g. outside the boilers	F22D7/08	F22D7/08		122
F22D7/10	10	within the boilers	F22D7/10	F22D7/10		21
F22D7/12	8	Control devices	F22D7/12	F22D7/12		52
F22D7/14	8	specially adapted for locomotive boilers	F22D7/14	F22D7/14		16
F22D11/00	7	Feed-water supply not provided for in other main groups	F22D11/00	F22D11/00		716
F22D11/003	8	{Emergency feed-water supply}	F22D11/00	F22D11/00		36
F22D11/006	8	{Arrangements of feedwater cleaning with a boiler}	F22D11/00	F22D11/00		289
F22D11/02	8	Arrangements of feed-water pumps	F22D11/02	F22D11/02		423
F22D11/04	9	with means to eliminate steam formation	F22D11/04	F22D11/04		47
F22D11/06	9	for returning condensate to boiler	F22D11/06	F22D11/06		1364
