A flow indicating system that includes a conduit (102) that contains asubstance, wherein the conduit defines a path along which the substanceprimarily flows and a viewing port (154) attached to the conduit and theviewing port prevents substantially non-ambient atmosphere gases andsubstances from escaping therefrom and allows visualization of an internalspace defined by the viewing port. A flow indicator (138) that is positionedwithin the conduit so as to be viewed via the viewing port and is positionedso as to not to substantially interfere with a flow of the substance along thepath.
