Flow-limiting device for a pipe carrying a fluid or gaseous medium

Claim 1

A fow limiting device for a pipe carrying a fluid or gaseous medium, said medium flowing in a first direction, comprising: a housing having a bore therethrough; an annular rib extending part way around the circumference of said bore, said annular rib further extending radially into said bore; a flap member mounted in said bore adjacent said annular rib for movement with respect to said annular rib; means for mounting said flap member for movement in said bore, said mounting means connecting said flap member to said annular rib, said means for mounting said flap member further comprising resilient biasing means connecting said partial annular rib to said flap member such that said resilient means urges said flap member in a direction opposite said first direction of flow and thereby increase said cross-sectional area of flow through the pipe in dependence on the kinetic energy differential of the medium upstream and downstream of the flap member; and said flap member further being shaped to have a space between said flap member and the internal wall of the bore which together with that portion of the circumference of the bore not having an annular rib portion defines a passage to provide flow through the pipe when the flap member is positioned to provide a minimum cross-section area of flow through the pipe.