An ultrasonic liquid delivery device (21, 421, 821) comprising: a housing (23, 423, 823) having an internal chamber (55, 455, 855) and at least one exhaust port (83, 483, 883) in fluid communication with the internal chamber (55, 455, 855) of the housing (23, 423, 823) whereby liquid within the chamber (55, 455, 855) exits the housing (23, 423, 823) at said at least one exhaust port (83, 483, 883); a valve member moveable relative to the housing (23, 423, 823) between a closed position in which liquid within the internal chamber (55, 455, 855) is inhibited against exhaustion from the housing (23, 423, 823) via the at least one exhaust port (83, 483, 883), and an open position in which liquid is exhaustable from the housing (23, 423, 823) via the at least one exhaust port (83, 483, 883); an ultrasonic waveguide (121, 521) separate from the housing (23, 423, 823) and valve member, the waveguide (121, 521) being disposed at least in part within the internal chamber (55, 455, 855) of the housing (23, 423, 823) to ultrasonically energize liquid within the internal chamber (55, 455, 855) prior to said liquid being exhausted from the housing (23, 423, 823) through the at least one exhaust port (83, 483, 883) in the open position of the valve member; an excitation device (145, 545, 945) operable in the open position of the valve member to ultrasonically excite said ultrasonic waveguide (121, 521), wherein the waveguide (121, 521) is elongate and is generally tubular along at least a portion thereof, said tubular portion having a terminal end disposed within the internal chamber (55, 455, 855) of the housing (23, 423, 823), and wherein the tubular portion of the waveguide (121, 521) defines an interior passage within the waveguide (121, 521); and a mounting member (79, 479, 879) interconnecting the waveguide (121, 521) and the housing (23, 423, 823), said mounting member (79, 479, 879) being configured to substantially vibrationally isolate the housing (23, 423, 823) from the waveguide (121, 521); characterised by said valve member being elongate and at least in part extending generally coaxially within the interior passage of the tubular portion of the waveguide (121, 521). a housing (23, 423, 823) having an internal chamber (55, 455, 855) and at least one exhaust port (83, 483, 883) in fluid communication with the internal chamber (55, 455, 855) of the housing (23, 423, 823) whereby liquid within the chamber (55, 455, 855) exits the housing (23, 423, 823) at said at least one exhaust port (83, 483, 883); a valve member moveable relative to the housing (23, 423, 823) between a closed position in which liquid within the internal chamber (55, 455, 855) is inhibited against exhaustion from the housing (23, 423, 823) via the at least one exhaust port (83, 483, 883), and an open position in which liquid is exhaustable from the housing (23, 423, 823) via the at least one exhaust port (83, 483, 883); an ultrasonic waveguide (121, 521) separate from the housing (23, 423, 823) and valve member, the waveguide (121, 521) being disposed at least in part within the internal chamber (55, 455, 855) of the housing (23, 423, 823) to ultrasonically energize liquid within the internal chamber (55, 455, 855) prior to said liquid being exhausted from the housing (23, 423, 823) through the at least one exhaust port (83, 483, 883) in the open position of the valve member; an excitation device (145, 545, 945) operable in the open position of the valve member to ultrasonically excite said ultrasonic waveguide (121, 521), wherein the waveguide (121, 521) is elongate and is generally tubular along at least a portion thereof, said tubular portion having a terminal end disposed within the internal chamber (55, 455, 855) of the housing (23, 423, 823), and wherein the tubular portion of the waveguide (121, 521) defines an interior passage within the waveguide (121, 521); and a mounting member (79, 479, 879) interconnecting the waveguide (121, 521) and the housing (23, 423, 823), said mounting member (79, 479, 879) being configured to substantially vibrationally isolate the housing (23, 423, 823) from the waveguide (121, 521); characterised by said valve member being elongate and at least in part extending generally coaxially within the interior passage of the tubular portion of the waveguide (121, 521).