Monitoring rod

摘要

Cigarette rod or cigarette filter rod comprising an outer, longitudinally seamed wrapper is monitored, to detect defects in the longitudinal seam, by directing, from a nozzle, a stream of air tangentially of the rod, whereby the air flows in Coanda effect contact with the rod, and audio detecting the presence or absence of air, at a location spaced from the nozzle, in accordance with the presence or absence of a seam defect.