Patent ID: 8903235

Claim:
A closure element ( 1 ; 101 ; 301 ; 401 ; 501 ) adapted to be installed in a vessel wall ( 50 ) provided with an aperture, said closure element comprising: at least one peripheral flange ( 2 ; 102 ); and a central cover unit ( 3 ; 103 ), said central cover unit covering said aperture; at least one light source ( 41 ; 141 ) provided within a predefined zone ( 35 ; 135 ; 335 ; 435 , 436 ; 535 , 536 ) located in the central cover unit ( 3 ; 103 ), wherein the closure element is a cleaning cover ( 1 ; 101 ) which is openable, and the at least one flange ( 2 ; 102 ) is circumferential and located at an edge portion of the central cover unit ( 3 ; 103 ), wherein the central cover unit ( 3 ; 103 ; 203 ) includes at least one transparent section ( 32 ; 132 ; 232 ) constituting said predefined zone ( 35 ; 135 ; 335 ; 435 , 436 ; 535 , 536 ), and said at least one light source ( 41 ; 141 ) is confined within the central cover unit ( 3 ; 103 ), and wherein the flange is substantially flush with an interior side of the vessel wall.