Valve assembly

Valve assembly for use within a flow path for permitting relatively free flow in a first direction and for preventing flow in said path in a second, opposite direction, comprising:

• a housing defining a housing interior having an interior surface and having first and second ports opening into said housing;
• a flow regulator constructed as a single piece from a resilient material, said regulator including a pair of planar lips arranged in a converging relationship to define for said regulator an open end and a normally closed end whereat said lips are disposed adjacent each other to define a normally closed slit therebetween, said regulator further including at least one side wall interconnecting said lips, said lips and said side wall defining inner and outer planar surfaces for said regulator;
• means for securing said regulator within said housing interior with said normally closed end toward said second port and said open end toward said first port;
• and
• means for forming a seal between said open end of said regulator and said housing interior so that flow in said first direction is from said first port, through said open end, through said normally closed end, and to said second port;
• said housing interior defining a shape and size substantially identical to the shape and size of said outer surface of said regulator such that said regulator is secured within said housing with said outer surface of said regulator adjacent said interior surface of said housing when said normally closed end of said regulator is closed;
• and
• said first and said second ports each having a cross-sectional area smaller than any cross-sectional area of said housing interior, said second port opening into said housing immediately adjacent said normally closed end of said regulator.