| 摘要 |
<p>A diffuser for use in submerged conditions, e.g. for aerating sewage, comprises an elongate material strip made from two separate sheets 1, 2 of synthetic plastics material which are separately perforated in two lateral zones 1a, 1b and 2a, 2b and then heat sealed together at their longitudinal edges 3, 4 and at intermediate positions 5, 6 to either side of a steel cable 7 positioned between the sheets 1 and 2. The steel cable 7 is arranged to act as a negative buoyancy aid. When air is supplied to the tubes 8, 9 they distend into an inflated condition and air passes into the surrounding medium through the tube perforations. The cable may be replaced by metal strips (77, Fig 16, not shown). Various other forms of diffusers are also disclosed, including one of circular design. The perforations are self-closing, and their proximity and the elasticity of the material are such that internal pressures cause a synchronous opening and closing of the perforations (Fig 21, not shown). <IMAGE></p> |
