Thermoplastic check valve

Claim 2

A valve element adapted for insertion within a section of tubular plastic pipe, said valve element comprising: a ring; a cover, a flexible web integral with said ring and cover; said ring having a diameter such that it will fit snugly within the section of tubular plastic pipe, said ring having a sealing surface adapted to mate with a corresponding surface in said section of tubular plastic pipe; said cover having an outer diameter less than the outer diameter of the ring whereby the cover can swing open and closed by means of the flexible web, said cover having a marginal sealing surface sufficiently resilient to effect a liquid seal when urged against said ring; and, said flexible web integral with said ring and cover being sufficiently resilient to permit said cover to swing open and closed in response to the flow of fluids through said pipe system incorporating said valve element.

Claim 3

The valve of claim 1 wherein the cover has a convex shape.

Claim 4

The valve element of claim 2 wherein said cover has radially disposed supporting ribs.

Claim 5

A plastic check valve comprising in combination a tubular plastic increaser bushing and a vAlve element adapted for insertion in said increaser bushing; said increaser bushing having a first end and a second end, the inner diameter of said first end being larger than the inner diameter of said second end, said inner wall of said increaser bushing beveled to the point where the diameter changes from said first end to said second end; said valve element having a ring, cover flexible web integral with said ring and cover, said ring being adapted to fit snugly within the first end of said increaser bushing, said ring having a sealing surface adapted to mate with the internal beveled edge of said increaser bushing, and said cover having a diameter less than the outer diameter of said ring so that said cover can swing open between an open position and a closed position by means of said flexible web which is sufficiently resilient to permit said cover to swing open and closed in response to the flow of fluids through said check valve and whereby the area of the opening when said cover is in the open position is at least equal to the area of the opening in the second section of pipe in which said ring is inserted.

Claim 6

A plastic check valve comprising in combination a tubular plastic increaser bushing and a vAlve element adapted for insertion in said increaser bushing; said increaser bushing having a first end and a second end, the inner diameter of said first end being larger than the inner diameter of said second end, said inner wall of said increaser bushing beveled to the point where the diameter changes from said first end to said second end; said valve element having a ring, cover flexible web integral with said ring and cover, said ring being adapted to fit snugly within the first end of said increaser bushing, said ring having a sealing surface adapted to mate with the internal beveled edge of said increaser bushing, and said cover having a diameter less than the outer diameter of said ring so that said cover can swing open between an open position and a closed position by means of said flexible web which is sufficiently resilient to permit said cover to swing open and closed in response to the flow of fluids through said check valve and whereby the area of the opening when said cover is in the open position is at least equal to the area of the opening in the second section of pipe in which said ring is inserted.