Design considerations for baffles in Sudbury International expansion joints

Flow liners, or baffles, are an important part of fabric expansion joints.

Sudbury International Engineered Products Limited is a valuable Canadian source of non-metal expansion joints for ducting systems. The manufacturers who provide these joints consider many design considerations for components, frames, clamping devices, and other parts. Another important area for consideration is baffles.

Also known as flow liners, baffles have a design closely associated with the frame design in non-metal expansion joints, and part of the frame often forms each baffle.

Three kinds of flow liners

The shape of the baffles in Sudbury International’s fabric expansion joints is a major design aspect meant to eliminate restriction of movement. The primary function is to prevent the erosion of the flexible element and pillow.

There are three basic types of flow liner. First, the telescopic baffle has an overlap that enables the use of a secondary fly ash barrier when necessary. The second type is the simple flanged type with single baffle. The third, the weld-in baffle, has a shape governed by the frame design and movement requirements. The gap between the baffle and the frame and/or duct is typically limited to that required for lateral movement and both frame and ductwork tolerances, to make sure there are no interferences.

Other important baffle considerations that expansion-joint manufacturers must take into consideration:

• The type and thickness of material in relationship to the possibility of erosion and corrosion;
• The length of each section of the baffle, which has to be addressed to compensate for thermal growth;
• Requirements for duct washing and the need to protect pillows, or fly ash barriers, and flexible elements;
• Operating temperature, which must be considered for baffles that are attached by welding before design of the welded connection;
• The gap between the baffle and all other components, which should be considered in order to prevent interference; and
• Internal baffles, which must be designed so as not to entrap dust or condensation.

With strict, expert attention paid to the design by the manufacturers, Sudbury International’s line of non-metal expansion joints is guaranteed to operate at the peak of its ability.

For more information, contact Sudbury International.

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