Valve assembly

A valve assembly comprising:

• circumferential wall means defining a generally cylindrical valve chamber;
• inlet orifice means opening into said cylindrical chamber through said circumferential wall means;
• outlet means for said valve chamber;
• a valve member comprising a circular spring leaf having a contour generally similar to the contour of said circumferential wall means and arranged to extend circumferentially within said valve chamber;
• said spring leaf including a part thereof extending continuously over said inlet orifice means and into abutting engagement with parts of said circumferential wall means adjacent said orifice means to block fluid flow therethrough into said valve chamber;
• said spring leaf being arranged to be resiliently deflected by fluid pressure in said inlet orifice means to be lifted out of blocking engagement with said circumferential wall means to open said inlet orifice means when in said deflected state under the influence of said fluid pressure and to resiliently close said inlet orifice means when said fluid pressure is below a given limit;
• means operatively mounting said spring leaf within said valve chamber at a point thereon diametrically opposite to said part of said spring leaf extending over said inlet orifice means;
• said spring leaf being configured so that when undeflected by said fluid pressure its diameter is smaller than that of the internal diameter of said valve chamber and so that its circumferential region forming said part thereof extending over said inlet orifice means sealingly engages along an edge formed in said circumferential wall means surrounding said inlet orifice means;
• the diameter difference being selected in such a way that after its deflection by said fluid pressure to open said inlet orifice means, said spring leaf is spaced on all sides from said circumferential wall means.