VENTILATOR

PROBLEM TO BE SOLVED: To provide a ventilator to prevent contamination of the outer wall surface of a building. SOLUTION: A ventilator is constituted such that an outer flange part 3a situated at the peripheral edge surface of the internal release of a connecting body 3 on the front of which a number of blades are mounted coincides with an inside flange part 2a formed such that the peripheral edge part of the outer end surface of a cylindrical body 2 having opposite surfaces being released is extended externally to achieve the purpose described above. The ventilator is provided with a guide piece 4 having a diameter larger than the outside diameter of the outer flange part 3a and an inside diameter capable of making close contact with the outer peripheral surface of the cylindrical body 2. The guide piece 4 is formed in a lower half body being an approximately doughnut-form body in a front view. Meanwhile, a tank 5 is formed in a half- moon shape in a front view and in the shape of a container in a longitudinal section, the upper surface of which is released. The lower portion of the guide piece 4 is brought into close contact with a rear face wall 5b of the tank 5 to form a contamination preventing tool 9. Further, the guide piece 4 is locked by a screw internally of the outer flange part 3a with a given distance therebetween held and the contamination preventing tool 9 is mounted on the lower portion of the outside of the cylindrical body 2.