NOVELTY - The device (11) has a pipe section (13) i.e. T shaped connecting piece, with connecting flanges (15, 17) comprising an opening (16, 18), where the flanges are connected together by a tubing section. A connecting flange (19) with an opening (20) is provided at a passage (21) between the flanges (15, 17). An extended cross sectional region (33) provided in the section receives protective plates (23) that are arranged at a distance from each other. The plates are arranged in the region at a distance to the flange (19), where the plates are insertable and detachable through the flange (19).    USE - Safety device for protecting a high vacuum pump i.e. turbo-molecular pump, from harmful condensable steam i.e. metal vapor, in a vacuum system (all claimed) that is utilized for producing a vacuum in a semiconductor industry during production of photovoltaic cell e.g. copper indium gallium diselenide solar cell and copper indium diselenide cell.    ADVANTAGE - The protective plates protect the high vacuum pump such as turbo-molecular pump from unwanted condensable steam such as metal vapor in an effective manner. The protective plates are insertable and detachable through the opening in the connecting flange, so that the need to permanently arrange the protective plates in the passage is eliminated and the conductivity between the inner wall of the extended cross sectional region and the protective plates is improved. The detachable insertion of the protective plate allows cleaning and replacing of plate in a simple manner without the need to unscrew the pump. The protective plates are arranged at the connecting flange, thus eliminating the need of additional attachments or supports at the pipe section.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a vacuum system comprising a connecting flange.    DESCRIPTION OF DRAWING(S) - The drawing shows a front view of a safety device comprising a pipe section defining a straight passage with three connecting flanges and protective plates which are arranged in the passage.    Safety device (11)    Pipe section (13)    Connecting flanges (15, 17, 19)    Openings (16, 18, 20)    Passage (21)    Protective plates (23)    Extended cross sectional region (33)