A valve apparatus is integrally molded from an elastomeric material so as to form a valve seating portion including a valve opening, a valve member and connective strands extending from the valve seating portion to the valve member. The valve member is initially molded on one side of the valve opening,...http://www.google.fr/patents/US4375825?utm_source=gb-gplus-shareBrevet US4375825 - Integral valve apparatus
