BottleBot – the right cork for the bottle
General Information
For bottle necks according to DIN EN 12726, an average diameter of 20 mm can be assumed (measured 50 mm below the top of the bottle opening). The actual neck profile, however, varies from bottle to bottle.
Headspace = the air space between the wine surface and the natural cork.
The filling level value (for a nominal filling volume at 20 °C) can be determined by calibration (measuring by volume) or taken from the information on the bottle base:
As a rule, the filling height of a bottle up to the nominal volume (750 ml) is indicated by an embossing on the bottle base. This can be stated either as the distance from the top of the bottle opening in millimetres (e.g. 55 mm, 63 mm, 70 mm) or as the brimful volume in centilitres (e.g. 76.7 or 77, in both cases without the unit “cl”). The following values correspond: 55 mm → 76.7 cl / 63 mm → 77 cl
CO₂ content leads to outgassing when the temperature increases, resulting in an additional rise in internal bottle pressure.
The internal bottle pressure can be measured using a pressure gauge (needle manometer). Typical values for corking with a properly functioning vacuum system range between –0.2 and 0.2 bar. Without pressure-reducing measures, values can exceed 3 bar when the headspace is small.
Theoretical internal bottle pressure: If the remaining headspace approaches zero, the pressure theoretically approaches infinity. In practice, however, the pressure is partially released between the bottle wall and the cork, pushing the cork out of the bottle or, in extreme cases, causing the bottle to burst.