| 摘要 |
<p>Container (1) in the form for example of an expansion tank in a cooling system, with an outside wall (5) comprising an at least partly translucent plastic material whose opacity increases with age, and a marker (6) for indicating ageing of the plastic material. The marker is so arranged as to only be visible from the outside of the container through the outside wall so long as the opacity of the outside wall is less than that corresponding to a certain degree of ageing of the plastic material. A method for estimating ageing of a said plastic material comprises placing a marker in a container with an outside wall comprising the plastic material, visual inspection of the marker through the outside wall and using said inspection as a basis for estimating the degree of ageing of the plastic material. The marker is arranged to only be visible through the outside wall so long as the opacity is less than that corresponding to a certain degree of ageing of the plastic material.</p> |
