by Dan Capwell
In conventional pneumatic conveying systems, materials impact the elbow wall at high speed to change direction. As a result, abrasive materials can wear through the elbow wall, fragile materials can break apart, and heat-sensitive materials can build-up and clog the elbow. When plastic pellets impact and heat the elbow wall, they often melt, forming streamers, angel hair and snakeskins.
A simple maintenance step to prevent these problems is to replace conventional sweep elbows, ceramic-backed elbows and plugged-tee elbows with deflection elbows that prevent material from impacting the elbow wall.
Deflection elbows, also known as vortex elbows, employ a spherical chamber that protrudes partially beyond the desired 90° or 45° pathway, causing a ball of material suspended in air to rotate. Since the ball of material rotates in the same direction as the airstream that powers it, incoming material is cushioned by the ball’s rotation, and is gently deflected around the bend. As a result, elbow wear, material degradation, and melting/plugging problems are virtually eliminated.