摘要 |
The neck of a bottle is closed and sealed by a one-piece cap having a cylindrical portion which surrounds the neck, a deformable end wall which extends across the open end of the neck, and a flexible hose which is integral with the end wall. The outer side of the end wall has a diametrically extending projection consisting of two discrete sections having flat elongated outer surfaces which are parallel to each other when the pressure in the bottle equals the pressure of the surrounding atmosphere and which are inclined with respect to each other when the pressure inthe interior of the bottle is reduced below atmospheric pressure. The person observing the surfaces of the two sections can ascertain the presence and absence as well as the extent of pressure differential between the interior and exterior of the bottle. |