"1. A non-return valve (3), characterized in that it has a component (4) having
comprising an inlet section (5) in the form of a self-supporting troughshaped section and an outlet section, the outlet section being made of a
flexible resilient material connected to the inlet section (5), whereby the
outlet section comprises a flat flexible resilient strip (6) of flexible resilient material with a high inherent degree of flexibility, the strip (6) terminating at one
end in a self-supporting trough-shaped section (5) being connected with the inlet section (5) at its upper edge; and a complementary further comprising a
component that is separate from the strip (6)