A sight flow apparatus includes a body designed to be connected in-line to fluid pipes within a manufacturing plant or other facility. One or more window assemblies are removably mounted on the sides or ends of the body to allow visual inspection of fluid flow through the body cavity. A fluid indicator device i.e., a flapper assembly or a rotor assembly, is mounted within the body cavity and supported by an axle extending between the windows, between the body itself, or between a pair of alignment washers located within the body. The rotor assembly includes a plurality of planar blades which are interconnected to form generally radially extending vanes. An enlarged indicator cap is coupled to each end of the rotor assembly to improve visual examination of fluid flow effects, to lock the interconnected blades together and to prevent the blades from contacting the windows, alignment washer or body. The flapper assembly for the sight flow apparatus includes a single blade which is coupled on each end to the axle with an enlarged indicator cap. The indicator cap on the rotor assembly and the flapper assembly facilitate visually inspecting the fluid flow through the windows in the sight flow apparatus over a wide range of fluid conditions.