A fluid delivery device comprising a mounting element for connection to a fluid supply (7,9) and a body element mounted on the mounting element for controlling discharge of fluid from the device, the body element being detachable from the mounting element without disconnecting the mounting element from the fluid supply (7,9), and the mounting element including an isolator valve assembly (49, 51) having an open position to connect the fluid supply (7, 9) to the body element when the body element is mounted on the mounting element and a closed position to isolate the fluid supply (7, 9) when the body element is removed from the mounting element, wherein the isolator valve assembly (49, 51) moves between the open and closed positions as the body element is attached to and detached from the mounting element, the isolator valve assembly comprising: an isolator plate mounted for rotation relative to the mounting element between end positions defined by engagement of a lug on the edge of the isolator plate with opposite ends of a slot in a sidewall of the mounting element, and comprising two outlet ports (67, 69), the outlet ports (67, 69) extending above the isolator plate and being received in a pair of inlet ports (75, 77) in the body element such that the isolator plate rotates with the body element, the outlet ports (67, 69) being provided with seals received in annular grooves (79, 81) to provide a watertight seal with the inlet ports (75, 77) in the body element; and an isolator plate seal arranged to seal between the underside of the isolator plate and the mounting element, the isolator plate seal being located in a channel in the underside of the isolator plate so as to rotate with the isolator plate and comprising inner and outer rings (63, 65) arranged to prevent water leaking between the mounting element and the isolator plate at the inner and outer peripheries, the inner and outer rings (63, 65) being joined together by a plurality of connecting webs which seal around the two outlet ports (67, 69) and divide the region between the outlet ports (67, 69) into three areas (71a,b,c) on one side of the ports and three areas (73a,b,c) on the other side, and wherein inlet ports (59, 61) in the mounting element connect the fluid supply (7, 9) to a region between the inner and outer rings (63, 65) of the isolator plate seal via inlets (15, 17) in the underside of the mounting element. an isolator plate mounted for rotation relative to the mounting element between end positions defined by engagement of a lug on the edge of the isolator plate with opposite ends of a slot in a sidewall of the mounting element, and comprising two outlet ports (67, 69), the outlet ports (67, 69) extending above the isolator plate and being received in a pair of inlet ports (75, 77) in the body element such that the isolator plate rotates with the body element, the outlet ports (67, 69) being provided with seals received in annular grooves (79, 81) to provide a watertight seal with the inlet ports (75, 77) in the body element; and an isolator plate seal arranged to seal between the underside of the isolator plate and the mounting element, the isolator plate seal being located in a channel in the underside of the isolator plate so as to rotate with the isolator plate and comprising inner and outer rings (63, 65) arranged to prevent water leaking between the mounting element and the isolator plate at the inner and outer peripheries, the inner and outer rings (63, 65) being joined together by a plurality of connecting webs which seal around the two outlet ports (67, 69) and divide the region between the outlet ports (67, 69) into three areas (71a,b,c) on one side of the ports and three areas (73a,b,c) on the other side,