Fluid visual inspection device

A fluid visual inspection device, comprising at least:

• a fluid visual inspection portion including a vane holder, a vane, a transparent duct, a partition and a plurality of rubber pads, the vane holder being a hollow barrel and having mating holding bars, the vane being hinged on the holding bars, the vane holder also including a first flange and a second flange extended from two ends of the holding bars and a third flange and a fourth flange extended from two ends of the first and second flanges that have respectively an external threaded portion, the transparent duct being coupled on the vane holder from an outer side, the partition being located at one end of the third or fourth flange and having an upper side to form a passage opening with the vane holder;
• and
• one set of fastening caps each including an internal screw hole at one end mating the external threaded portion of the third and fourth flanges and screw opening at another end communicating with the internal screw hole.