Self-cleaning rotary viewing hole and centrifugal machine provided with said rotary viewing hole

A fluid treatment chamber with a self-cleaning rotary sight window, the self-cleaning rotary sight window including:

• a stationary frame attached to a casing of the fluid treatment chamber by a first leak-tight joint;
• a rotary frame connected to the stationary frame by a rotary joint;
• a transparent stationary panel attached to the stationary frame by a second leak-tight joint;
• a transparent rotary panel, arranged opposite and spaced apart from the transparent stationary panel by an intermediate chamber, fitted into the rotary frame by a third leak-tight joint and in contact with the inside of the fluid treatment chamber, the intermediate chamber containing a modified atmosphere at a positive pressure above the pressure of the fluid treatment chamber, assuring a modified atmosphere leakage towards the fluid treatment chamber through the rotary joint;
• a modified atmosphere supply device connected to the intermediate chamber to provide and maintain the modified atmosphere at the positive pressure;
• a motor connected to the transparent rotary panel or to the rotary frame to cause the rotation thereof with respect to the stationary frame about an axis of rotation perpendicular to the transparent rotary panel.