An orifice valve for controlling the flow of bulk solids through an opening, said valve comprising: a housing comprised of two opposed sections each of which is a unitary body formed from a single piece of plate stock and presenting a first planar surface having an opening, two integral opposed sidewalls and an integral end wall, said walls (24, 28) each being perpendicular to said first planar surface and cooperating when said sections are placed in facing relationship to present a closed cavity, each of said sections further including a flange extending outwardly from each of said sidewalls and presenting a second planar surface parallel to said first planar surface, said flanges mating with one another when said sections are placed in facing relationship; a seal sandwiched between said second planar surfaces of the flanges; a blade received in said cavity and reciprocal between open and closed positions, said blade having an opening which aligns with said openings in said housing in the open position and having a solid section which blocks said housing openings in the closed position; and a plurality of retainers which hold said sections in rigid facing relationship, characterized in that the valve further comprises: a first pressure plate between said blade and the first housing section; a second pressure plate between said blade and the second housing section; and a plurality of compressible buttons mounted on a solid portion of each pressure plate in spaced apart relationship, the compressible buttons being positioned between the first pressure plate and the first housing section and between the second pressure plate and the second housing section, respectively. a housing comprised of two opposed sections each of which is a unitary body formed from a single piece of plate stock and presenting a first planar surface having an opening, two integral opposed sidewalls and an integral end wall, said walls (24, 28) each being perpendicular to said first planar surface and cooperating when said sections are placed in facing relationship to present a closed cavity, each of said sections further including a flange extending outwardly from each of said sidewalls and presenting a second planar surface parallel to said first planar surface, said flanges mating with one another when said sections are placed in facing relationship; a seal sandwiched between said second planar surfaces of the flanges; a blade received in said cavity and reciprocal between open and closed positions, said blade having an opening which aligns with said openings in said housing in the open position and having a solid section which blocks said housing openings in the closed position; and a plurality of retainers which hold said sections in rigid facing relationship, characterized in that the valve further comprises: a first pressure plate between said blade and the first housing section; a second pressure plate between said blade and the second housing section; and a plurality of compressible buttons mounted on a solid portion of each pressure plate in spaced apart relationship, the compressible buttons being positioned between the first pressure plate and the first housing section and between the second pressure plate and the second housing section, respectively. a first pressure plate between said blade and the first housing section; a second pressure plate between said blade and the second housing section; and a plurality of compressible buttons mounted on a solid portion of each pressure plate in spaced apart relationship, the compressible buttons being positioned between the first pressure plate and the first housing section and between the second pressure plate and the second housing section, respectively.