Ducted Air Systems
Expansion joints are required in large ducted air systems to allow fixed pieces of piping to be largely free of stress as thermal expansion occurs. Bends in elbows also can accommodate this. Expansion joints also isolate pieces of equipment such as fans from the rigid ductwork thereby reducing vibration to the ductwork as well as allowing the fan to “grow” as it comes up to the operating air system temperature without putting stress on the fan or the fixed portions of ductwork.
An expansion joint is designed to allow deflection in the axial (compressive), lateral (shear), or angular (bending) deflections. Expansion joints can be non-metallic or metallic (often called bellows type). Non-metallic can be a single ply of rubberized material or a composite made of multiple layers of heat and erosion resistant flexible material. Typical layers are: outer cover to act a gas seal, a corrosion resistant material such as Teflon, a layer of fiberglass to act as an insulator and to add durability, several layers of insulation to ensure that the heat transfer from the flue gas is reduced to the required temperature and an inside layer.
A bellows is made up of a series of one or more convolutions of metal to allow the axial, lateral or angular deflection required(Note: If required).
Read more about this topic: Expansion Joint
Famous quotes containing the words air and/or systems:
“I wonder whether mankind could not get along without all these names, which keep increasing every day, and hour, and moment; till at the last the very air will be full of them; and even in a great plain, men will be breathing each other’s breath, owing to the vast multitude of words they use, that consume all the air, just as lamp-burners do gas.”
—Herman Melville (1819–1891)
“What is most original in a man’s nature is often that which is most desperate. Thus new systems are forced on the world by men who simply cannot bear the pain of living with what is. Creators care nothing for their systems except that they be unique. If Hitler had been born in Nazi Germany he wouldn’t have been content to enjoy the atmosphere.”
—Leonard Cohen (b. 1934)