Today in 1984, US Patent DE 3235563 A1 was issued, an invention of Karl Horst Knopf, for his “Siphon Bottle Filling Apparatus.” Here’s the Abstract:
Traditional German siphon bottles are for the most part filled at the publican’s beer dispensing tap. In order to make possible filling without foaming and release of carbon dioxide, according to the invention a filling closure has been created which allows the bottle, prior to filling, to be put under pressure by means of a hand pump attached to the filling closure. No foam can form as the beer flows in, since the beer enters under counter-pressure and cannot expand. To regulate further overpressure building up as the beer flows in, a vent screw is provided.
