| 摘要 |
A tubular element, for acoustic unitary sanitation downpipes in buildings, is made by extrusion or injection moulding of thermoplastic material and consists of (a) a rigid external protective sleeve (3) of rigid PVC and (b) a flexible internal acoustic sleeve (2) of filled plasticised PVC with a Shore hardness of 65-85, the interior wall of the acoustic sleeve having continuous helical threads (4) made of the same material as the sleeve. Pref. the acoustic sleeve (2) contains, apart from mineral filler and fire-proofing agent, a biocide (esp. oxy-bisphenoxyarsine) to prevent plasticiser degradation. |
