| 摘要 |
<p>The dimension of the corrugations of the flexible duct for air conditioning and heating systems are chosen to allow an elbow neutral axis radius of curvature approximately equal to the duct diameter. One or several layers of metallic sheet are spirally wound to form the walls of the duct, the sheets being corrugated and the windings such that adjacent sheet edges overlap. For ducts of 200mm to 600 mm. diameter, the corrugation heigh is equal to or greater than 4mm., the ratio between the height and wall thickness (s) is esqual to or greather than 18 and the ratio between height and pitch (t) of the corrugations lies between 0.8 and 1.0.</p> |
