Below is a chart comparing various types of elbow designs and how they perform against specific elbow-related problems in a pneumatic conveying system. Each elbow is rated by various categories including degradation, noise levels, downtime and costs. They can range on a scale of excellent to poor in relation to how that specific elbow performs in each situation.
HammerTek Elbow Room
SMART ELBOW® Deflection Elbow for Pneumatic Conveying Systemsress site