| abstract |
A metered dose dispensing valve for dispensingnmetered volumes of a pressurised aerosol formulation, thenvalve comprising a cylindrical passage or chamber (656) and anvalve stem (662) movable relative to said passage or chamber (656)nsuch that in at least some of its possible positions thenvalve stem (662) forms a gas-tight seal with a wall of saidnpassage or chamber (656) by means of an annular sealing element (670,672)nof resiliently deformable material located around thenvalve stem (662) wherein said annular sealing element (670,672) has anconfiguration which facilitates deformation thereof innresponse to forces generated during movement of saidnvalve stem relative to the passage or chamber to reducenfrictional forces and maintain a gas-tight seal. |