An apparatus for contaminant reduction in a stream of compressed gas, the apparatus comprising:- a first insert for directing a stream of compressed gas; a head portion including an inlet for receiving a stream of compressed gas, an outlet for said gas, an inlet pathway for directing said gas from said inlet towards said first insert and an outlet pathway for directing said gas from said first insert towards said outlet; a body portion for collecting contaminants removed from said gas and connected to and sealed relative to said head portion, said body portion including a drain port for exhausting said contaminants after removal from said stream of compressed gas, wherein said first insert is located within a volume formed by said head and body portions (14, 16), the insert comprising:- a tubular portion connected to the head portion such that the gas from the inlet pathway engages said insert externally of said tubular portion and the gas passes to the outlet pathway from internally of said tubular portion, at least one baffle extending from said tubular portion and thereby narrowing a substantially annular gap between said insert and a wall of at least one of said body and head portions (14, 16), and at least one curved wall extending from said baffle for causing said stream of compressed gas to rotate around an axis of said tubular portion and thereby form a vortex, characterized in that said insert comprises a plurality of curved walls, said walls extending radially outwards beyond said baffle and forming retaining portions at distal ends of said walls for engaging at least one of said body and head portions (14, 16). a first insert for directing a stream of compressed gas; a head portion including an inlet for receiving a stream of compressed gas, an outlet for said gas, an inlet pathway for directing said gas from said inlet towards said first insert and an outlet pathway for directing said gas from said first insert towards said outlet; a body portion for collecting contaminants removed from said gas and connected to and sealed relative to said head portion, said body portion including a drain port for exhausting said contaminants after removal from said stream of compressed gas, wherein said first insert is located within a volume formed by said head and body portions (14, 16), the insert comprising:- a tubular portion connected to the head portion such that the gas from the inlet pathway engages said insert externally of said tubular portion and the gas passes to the outlet pathway from internally of said tubular portion, at least one baffle extending from said tubular portion and thereby narrowing a substantially annular gap between said insert and a wall of at least one of said body and head portions (14, 16), and at least one curved wall extending from said baffle for causing said stream of compressed gas to rotate around an axis of said tubular portion and thereby form a vortex, characterized in that said insert comprises a plurality of curved walls, said walls extending radially outwards beyond said baffle and forming retaining portions at distal ends of said walls for engaging at least one of said body and head portions (14, 16). a tubular portion connected to the head portion such that the gas from the inlet pathway engages said insert externally of said tubular portion and the gas passes to the outlet pathway from internally of said tubular portion, at least one baffle extending from said tubular portion and thereby narrowing a substantially annular gap between said insert and a wall of at least one of said body and head portions (14, 16), and at least one curved wall extending from said baffle for causing said stream of compressed gas to rotate around an axis of said tubular portion and thereby form a vortex, characterized in that said insert comprises a plurality of curved walls, said walls extending radially outwards beyond said baffle and forming retaining portions at distal ends of said walls for engaging at least one of said body and head portions (14, 16).