| 摘要 |
PROBLEM TO BE SOLVED: To provide an air duct facilitating construction works and providing a large-sound reducing effect. SOLUTION: A silencer is so formed that an air passage of the air duct is divided and respective insides are formed of sound absorbing materials. The silencer comprises a square cylindrical casing 10 forming a fluid passage of the air duct and a plurality of sound reducing element 12 to be inserted in the square cylindrical casing 10. The sound reducing element 12 is formed of a cylindrical and inorganic-fiber ventilating pipe whose front/rear surfaces are covered with scattering preventive materials 22 and 23 formed of a permeable inorganic fiber, an organic fiber, a glass cloth, or an unwoven fabric. |
