TYPES OF BOILERS Generally speaking, a steam boiler is a closed metallic vessel in which steam is generated from water by the application of heat. As steam is under pressure it is evident that the vessel must be strong and tight.
To operate the boiler safely and economically there must be certain fittings and accessories—some of these are used in the care of the boiler, while others serve to increase the economy. Among the most important attachments and appurtenances may be mentioned the following: A feed pump or injector, with valves, piping, etc., to supply water to the boiler.
Gage cocks and glass water gage to show the attendant the height of water or the water level, as it is called, in the boiler.
A pressure gage to show the pressure of steam in the boiler. The pressure is usually measured in pounds per square inch.
A safety valve to allow steam to escape from the boiler when the pressure exceeds a certain fixed amount. This attachment, being a safety device, should be automatic and reliable.
A pipe, with its valves, to blow out sediment from the boiler, reduce the amount of water in the boiler, or empty it.
A steam pipe, with its valves, to conduct the steam from the boiler to the place were it is to be used.
Manholes and handholes, with covers, for examination, repairs, and cleaning.
* Fusible plugs to give warning when the water level becomes too low, or melt and allow. the water to escape.
* and alarms to give warning when the water level is too high or too low.
* A heater to raise the temperature of the feed water as nearly as possible to that of the water in. the boiler.
In addition to these there are other attachments such as: Lugs or brackets for supporting the boiler.
Masonry for setting the boiler and keeping it in position, and in many cases to keep the hot gases in contact with the shell.
Furnace fittings, including grate bars, bearer bars, dampers, fire doors, ashpit doors, etc.
The chimney to carry away the waste gases and create draft. Tools, such as shovels, slice bars, scrapers, tube brushes, etc.