A spray nozzle assembly including: a nozzle cap housing an insert; a nozzle body; wherein an upper face of the insert includes a recess for receiving or locating a primary seal that is adapted to abut a downwardly facing surface of the nozzle assembly; and the nozzle cap is adapted to compress towards the insert to compress the primary seal in the recess and against the downwardly facing surface; the spray nozzle assembly further comprising: a secondary seal located between a lower face of a lower periphery of the nozzle cap and a seat, the seat presenting an upwardly facing surface of the nozzle body, to hold the secondary seal compressively by the nozzle cap when assembled with the nozzle body; wherein the nozzle cap and the nozzle body are threadably engageable by screwing the nozzle cap and nozzle body together in an axial direction to effect axial compression on the secondary seal; the secondary seal is located in position by at least one skirt device extending from the lower periphery and axially overlapping the seat when the nozzle assembly is assembled; and the at least one skirt device has an inner wall and an outer wall that define a circular skirt groove facing downwardly towards the seat, which seat is circular and adapted to compress the secondary seal located in the skirt groove; characterised in that: the inner and outer walls (65a,b) define apertures, including a first outer wide annular channel and a second narrower channel, the first outer wide annular channel and second narrow channel providing the skirt groove. a nozzle cap housing an insert; a nozzle body; wherein an upper face of the insert includes a recess for receiving or locating a primary seal that is adapted to abut a downwardly facing surface of the nozzle assembly; and the nozzle cap is adapted to compress towards the insert to compress the primary seal in the recess and against the downwardly facing surface; the spray nozzle assembly further comprising: a secondary seal located between a lower face of a lower periphery of the nozzle cap and a seat, the seat presenting an upwardly facing surface of the nozzle body, to hold the secondary seal compressively by the nozzle cap when assembled with the nozzle body; wherein the nozzle cap and the nozzle body are threadably engageable by screwing the nozzle cap and nozzle body together in an axial direction to effect axial compression on the secondary seal; the secondary seal is located in position by at least one skirt device extending from the lower periphery and axially overlapping the seat when the nozzle assembly is assembled; and the at least one skirt device has an inner wall and an outer wall that define a circular skirt groove facing downwardly towards the seat, which seat is circular and adapted to compress the secondary seal located in the skirt groove; characterised in that: a secondary seal located between a lower face of a lower periphery of the nozzle cap and a seat, the seat presenting an upwardly facing surface of the nozzle body, to hold the secondary seal compressively by the nozzle cap when assembled with the nozzle body; wherein the nozzle cap and the nozzle body are threadably engageable by screwing the nozzle cap and nozzle body together in an axial direction to effect axial compression on the secondary seal; the secondary seal is located in position by at least one skirt device extending from the lower periphery and axially overlapping the seat when the nozzle assembly is assembled; and the at least one skirt device has an inner wall and an outer wall that define a circular skirt groove facing downwardly towards the seat, which seat is circular and adapted to compress the secondary seal located in the skirt groove; characterised in that: the inner and outer walls (65a,b) define apertures, including a first outer wide annular channel and a second narrower channel, the first outer wide annular channel and second narrow channel providing the skirt groove.