PTFE lined sight flow indicators have been designed for visually observing the flow of corrosive media. Except for the borosilicate glass, all wetted parts of the indicators are lined with PTFE. These units are ideal for viewing such corrosive fluids as acids, chlorides, sulfates, bleach solutions, solvents, and phenols. Each model can be provided with drip tubes. PTFE lined sight flow indicators are drilled to mate with ANSI Class 125/150 connections.