A fluid regulator, comprising: a housing including an upper housing portion and a lower housing portion, each of the upper and lower housing portions including a flange portion; a diaphragm movably disposed within the housing; a loading chamber defined by the upper housing portion and a first side of the diaphragm; an output pressure control chamber defined by the lower housing portion and a second side of the diaphragm opposite the first side, the diaphragm movable responsive to pressure changes in the output pressure control chamber; a loading spring disposed in the loading chamber and configured to bias the diaphragm toward the lower housing portion; a valve (202; 408) having a seat (204; 410), a valve disc (206; 411), and a stem (208; 412) coupled to the valve disc; a valve guide (210; 418) that holds the stem to maintain a sealing surface of the valve disc in a substantially coplanar relationship to the seat; and a lever disposed within the output pressure control chamber and having a first end coupled to the stem and a second end coupled to the diaphragm disposed within the fluid regulator, wherein the lever is movable responsive to movement of the diaphragm within the housing, and wherein the lever is coupled to the stem to apply a force to the stem in a direction that is non-parallel to a longitudinal axis of the stem and to load the valve stem against a surface of the valve guide, characterised in that each flange portion having a first radius defining an inner portion of the flange portion and a second radius greater than the first radius that defines a mounting envelope of the fluid regulator; wherein each flange portion includes a plurality of circumferentially spaced protrusions which have outer portions which extend to a third radius which is greater than the second radius; wherein each of the plurality of protrusions includes at least a pair of apertures (828, 830; 832, 834; 836, 838; 840, 842), each of the apertures in the pair configured to receive a fastener, each of the apertures of each of the flange portions positioned to engage a corresponding aperture in the other one of the flange portions, and wherein the circumferential spacing between the pair of apertures per protrusion is less than the spacing between adjacent apertures on adjacent protrusions, wherein the stem (208; 412) includes a stop (228; 422) configured to limit the travel of the valve disc (206; 411) toward the seat (204; 410), wherein the stop (228; 422) is integrally formed on the valve stem (208; 412). a housing including an upper housing portion and a lower housing portion, each of the upper and lower housing portions including a flange portion; a diaphragm movably disposed within the housing; a loading chamber defined by the upper housing portion and a first side of the diaphragm; an output pressure control chamber defined by the lower housing portion and a second side of the diaphragm opposite the first side, the diaphragm movable responsive to pressure changes in the output pressure control chamber; a loading spring disposed in the loading chamber and configured to bias the diaphragm toward the lower housing portion; a valve (202; 408) having a seat (204; 410), a valve disc (206; 411), and a stem (208; 412) coupled to the valve disc; a valve guide (210; 418) that holds the stem to maintain a sealing surface of the valve disc in a substantially coplanar relationship to the seat; and a lever disposed within the output pressure control chamber and having a first end coupled to the stem and a second end coupled to the diaphragm disposed within the fluid regulator, wherein the lever is movable responsive to movement of the diaphragm within the housing, and wherein the lever is coupled to the stem to apply a force to the stem in a direction that is non-parallel to a longitudinal axis of the stem and to load the valve stem against a surface of the valve guide, characterised in that each flange portion having a first radius defining an inner portion of the flange portion and a second radius greater than the first radius that defines a mounting envelope of the fluid regulator; wherein each flange portion includes a plurality of circumferentially spaced protrusions which have outer portions which extend to a third radius which is greater than the second radius; wherein each of the plurality of protrusions includes at least a pair of apertures (828, 830; 832, 834; 836, 838; 840, 842), each of the apertures in the pair configured to receive a fastener, each of the apertures of each of the flange portions positioned to engage a corresponding aperture in the other one of the flange portions, and wherein the circumferential spacing between the pair of apertures per protrusion is less than the spacing between adjacent apertures on adjacent protrusions, wherein the stem (208; 412) includes a stop (228; 422) configured to limit the travel of the valve disc (206; 411) toward the seat (204; 410), wherein the stop (228; 422) is integrally formed on the valve stem (208; 412).