Patent ID: 7681867

Claim:
A diffuser for an aeration system, comprising a base which has a major wall with a periphery, and which defines a central line that is normal to said major wall, said major wall having an outer major surface and an inner major surface which is opposite to said outer major surface, and which defines an inlet that is adapted to introduce thereinto an aerating gas from the aeration system to generate a back pressure, and that extends along the central line through said outer major surface to form thereon a valve seat; a valve member configured to engage said valve seat so as to close said inlet; and a diaphragm including, a central portion disposed to carry said valve member to place said diaphragm in a non-aerating position when said inlet is closed, a peripheral portion which surrounds said central portion, and which is secured to said periphery to form upstream and downstream sides separated by said diaphragm such that, when the back pressure at the upstream side is higher than an ambient pressure at the downstream side, said valve member is forced to move away from said valve seat to place said diaphragm in an aerating position, and a surrounding web segment which is interposed between said central portion and said peripheral portion, and which is configured to stay in abutment with said outer major surface in the non-aerating position, said surrounding web segment including a plurality of fibrous filaments which are arranged to form a textured structure with a plurality of pores of a dimension such that in the aerating position, the introduced aerating gas is permitted to be bubbled through said plurality of pores, and such that said abutment of said surrounding web segment with said outer major surface is sufficient to institute a barrier to guard against a back flow through each one of said pores immediately after the back pressure is set to drop below the ambient pressure.