Why is the baffle an important addition to an expansion joint?

Baffles are metal shields designed to protect the expansion joint from abrasive particles in the gas stream by directing the flow away from the expansion joint. Baffles also reduce fluttering caused by the air turbulence as it passes over the expansion joint. A baffle can also be employed as a heat deflector component of an overall thermal protection system.

The most prevalent baffle designs are:
1) Straight
2) Airfoil
3) Semi-Airfoil
4) Double sliding (“Z” Baffle)

The baffles may be installed in many ways.
1) Welded to the expansion joint frame
2) Welded to the duct plate
3) Bolted to the mounting flange
4) Designed as an integral part of the expansion joint