A discharge assembly for discharging a metered volume of a liquid held in a pressurised or pressurisable container, said assembly comprising: (i) a housing having a liquid inlet at a first end thereof, (ii) a valve stem having a body locating within said housing and having a head portion projecting from the second end of said housing, said valve stem being axially moveable relative to the housing between a first limit position at which the assembly is closed to liquid discharge and a second limit position for discharge of the metered volume, (iii) a chamber (2034a, 2034b) provided within the body of the valve stem and having a liquid inlet towards a first end of the chamber and a first fluid transfer passageway towards the opposite, second end of the chamber, said first fluid transfer passageway providing communication between the chamber and the exterior of the valve stem, (iv) a second fluid transfer passageway (2109, 2110, 2111) along the outside of the valve stem between the inlet of the housing and said first fluid transfer passageway, (v) a seat, (vi) a fin configured to interface with the seat to provide an interference seal, wherein the fin extends into the path of the seat by at least 0.1mm, and (vii) a liquid discharge element moveable along said chamber (2034a, 2034b) from a liquid primed position to a liquid discharged position to effect discharge of the metered volume of liquid, wherein the exterior of the valve stem and the interior of the housing are configured such that: (a) in the first limit position of the valve stem the second fluid transfer passageway (2109, 2110, 2111) is open to fluid flow, and (b) in the second limit position of the valve stem the fin and the seat interface to create a temporary interference seal between the interior of the housing and the exterior of the valve stem so as to close said second fluid transfer passageway (2109, 2110, 2111) to fluid flow. (i) a housing having a liquid inlet at a first end thereof, (ii) a valve stem having a body locating within said housing and having a head portion projecting from the second end of said housing, said valve stem being axially moveable relative to the housing between a first limit position at which the assembly is closed to liquid discharge and a second limit position for discharge of the metered volume, (iii) a chamber (2034a, 2034b) provided within the body of the valve stem and having a liquid inlet towards a first end of the chamber and a first fluid transfer passageway towards the opposite, second end of the chamber, said first fluid transfer passageway providing communication between the chamber and the exterior of the valve stem, (iv) a second fluid transfer passageway (2109, 2110, 2111) along the outside of the valve stem between the inlet of the housing and said first fluid transfer passageway, (v) a seat, (vi) a fin configured to interface with the seat to provide an interference seal, wherein the fin extends into the path of the seat by at least 0.1mm, and (vii) a liquid discharge element moveable along said chamber (2034a, 2034b) from a liquid primed position to a liquid discharged position to effect discharge of the metered volume of liquid, (a) in the first limit position of the valve stem the second fluid transfer passageway (2109, 2110, 2111) is open to fluid flow, and (b) in the second limit position of the valve stem the fin and the seat interface to create a temporary interference seal between the interior of the housing and the exterior of the valve stem so as to close said second fluid transfer passageway (2109, 2110, 2111) to fluid flow.