A sprinkler adapter, comprising: a substantially tubular housing, comprising: a central axis (A-A); a first end; a second end; a generally circular internal passageway extending from the first end to the second end and aligned with the central axis (A-A), the internal passageway including a generally circular receptacle formed at the second end with an internal thread for a threaded engagement with a fire protection sprinkler and an annular gasket chamber located between the first end and the internal thread with the gasket chamber and the receptacle aligned with one another and centered about the central axis (A-A), wherein the internal thread is located between the receptacle and the gasket chamber, the gasket chamber comprising a first gasket bearing surface, a second gasket bearing surface perpendicular to the central axis (A-A) and spaced from the first gasket bearing surface, and a generally circular internal wall between the first gasket bearing surface and the second gasket bearing surface, wherein the internal wall of the gasket is parallel to the central axis (A-A) and the second gasket bearing surface is closer to the receptacle than the first gasket bearing surface, an annular gasket disposed in the chamber having an unloaded state within the chamber and a loaded state defined by the threaded engagement of the internal thread and the fire protection sprinkler, the gasket in the unloaded state adjacent to an annular void defined by an annular expansion portion, the gasket having a central opening (34, 36) defining an area through which fluid can flow, wherein the housing comprises a self-supporting monolithic plastic about the internal thread characterised in that the first gasket bearing surface, second gasket bearing surface, and internal wall define a holding portion of the gasket chamber and the annular expansion portion of the gasket chamber, wherein the first gasket bearing surface includes a skewed portion extending from the central opening and that is skewed with respect to the central axis (A-A) and a curved or radiused transition or portion formed between the skewed portion and the internal wall. a central axis (A-A); a first end; a second end; a generally circular internal passageway extending from the first end to the second end and aligned with the central axis (A-A), the internal passageway including a generally circular receptacle formed at the second end with an internal thread for a threaded engagement with a fire protection sprinkler and an annular gasket chamber located between the first end and the internal thread with the gasket chamber and the receptacle aligned with one another and centered about the central axis (A-A), wherein the internal thread is located between the receptacle and the gasket chamber, the gasket chamber comprising a first gasket bearing surface, a second gasket bearing surface perpendicular to the central axis (A-A) and spaced from the first gasket bearing surface, and a generally circular internal wall between the first gasket bearing surface and the second gasket bearing surface, wherein the internal wall of the gasket is parallel to the central axis (A-A) and the second gasket bearing surface is closer to the receptacle than the first gasket bearing surface, an annular gasket disposed in the chamber having an unloaded state within the chamber and a loaded state defined by the threaded engagement of the internal thread and the fire protection sprinkler, the gasket in the unloaded state adjacent to an annular void defined by an annular expansion portion, the gasket having a central opening (34, 36) defining an area through which fluid can flow, wherein the housing comprises a self-supporting monolithic plastic about the internal thread characterised in that the first gasket bearing surface, second gasket bearing surface, and internal wall define a holding portion of the gasket chamber and the annular expansion portion of the gasket chamber, wherein the first gasket bearing surface includes a skewed portion extending from the central opening and that is skewed with respect to the central axis (A-A) and a curved or radiused transition or portion formed between the skewed portion and the internal wall.