Venting your way to better rotary valve performance — Part II
This two-part article explains how to improve the rotary valve feedrate to your pneumatic conveying system with proper venting. Part I, which appeared in October 1997, discusses how leakage occurs in a rotary valve, how to predict leakage flow, and how to determine your venting needs. Part II covers types of rotary valve vents, discusses selecting a passive or active vent system, explains how to troubleshoot vent system problems, and describes venting solutions in several case studies.
A vent is an opening in the rotary valve housing or in a related component. The vent releases the excess gas from leakage and thus prevents the gas from creating feed problems by flowing up into the material feed hopper, which can fluidize the material and reduce its bulk density. The vent at the rotary valve is part of a vent system that includes a vent pipe and sometimes other components for directing excess gas away from the valve.