| 摘要 |
<p>A circular seal (19) for the end face of a substantially cylindrical canister, the seal (19) having a substantially rectangular cross-section, and a recess (21) in one side thereof to reduce the area of said cross-section. In use the recessed area (21) of the seal (19) constitutes a weakened portion which will blow out elastically to relieve excess pressure.</p> |
