| 摘要 |
<p>Indicating means for indicating a pressure relationship between a first region at atmospheric pressure, for example a refrigerating compartment of a cooling appliance, and a second region separated from the first region by a boundary wall (12) and able to be evacuated to sub-atmospheric pressure comprises an element (14) incorporated in the wall (12) and arranged to be deflectable, for example by virtue of a flexible construction, between a first position (Fig. 3A) indicating equivalent pressures in the regions and a second position (Fig. 3B) indicating a lower pressure, in particular a desired level of vacuum, in the second region. The element may comprise a concavo-convex element which protrudes out of the second region before being deflected, and into the region after a reduction in pressure therein. Alternatively the element may retain the same shape, but be deflected towards the second region by means of a resilient corrugated annular section (figures 2A, 2B). The element may make on audible sound on deflection from the first position to the second position.</p> |
