Pipelines are different from tanks and vessels in that the sight glass is used to observe flow. The sight flow indicator is an assembly consisting of two opposed sight glasses mounted to a housing. This arrangement allows ambient light to illuminate the flow from behind. There are also versions using a tubular glass that admits more light and permits viewing from any angle. Another name for sight flow indicator is visual flow indicator.
More terms for sight glass.
Lumiglas® Sight Glass, Luminaires and Visulex Camera Systems can be found in the Pharmaceutical, Oil Refining, Food & Beverage Industries, Mining, Water Treatment, Power Generation and Port Operations. The applications are endless.