To reduce cost by commonizing parts.

It is furnished with a pipe fixing flange constituted by integrally providing a flange part 20a to be fixed on an installation surface (ceiling 14) and a cylindrical part 20b having a pipe insertion hole 24 on its center and formed projectively in the roughly rectangular direction from the flange part 20a, dimension of an inner diameter of a hole 24a on the inlet side into which a pipe 16a of the pipe insertion hole 24 is inserted is formed roughly the same dimension of an outer diameter of the pipe 16a, inclination of the pipe 16a inserted into the pipe insertion hole 24 at a part (region 26) where this inner diameter is increased is allowed, and the pipe 16a is devised to be insalled by inclining it against the installation surface.