A flow indicating system that includesa conduit (102) that contains a substance, whereinthe conduit defines a path along which the substanceprimarily flows and a viewing port (154) attached tothe conduit and the viewing port prevents substantiallynon-ambient atmosphere gases and substances fromescaping therefrom and allows visualization of aninternal space defined by the viewing port. A flowindicator (138) that is positioned within the conduit soas to be viewed via the viewing port and is positionedso as to not to substantially interfere with a flow of thesubstance along the path.
