| 摘要 |
The neck of a flask has an upper portion with a thread adapted for cooperating with an internal thread of a cylindrical screw cap. The cap has a lower portion carrying a radial male key which bears on a lower portion of the neck of the flask when the cap is screwed onto said neck; at least two concentrical annuluses are held by an inner ring in a cylindrical groove of the flask, and also in a groove formed in an upper portion of the lower annulus for the mobile annulus. The two annuluses are each formed with a walled passage for disengagement of the radial male key when the cap is unscrewed from the neck of the flask. The screw cap and the concentrical annuluses each having a guiding mark for vertical alignment of the male key and the walled passages. |
