Armature for a Solenoid Actuator

An armature (132; 232; 332) for a solenoid actuator is disclosed. The armature comprises a first face (170; 270; 370) comprising a recess (174; 274; 374) suitable for receiving a biasing spring in use of the armature; a second face (172; 272; 372) opposite the first face (170; 270; 370); and fluid communication means (178; 210; 310) for providing a fluid flow path through the armature between the recess (174; 274; 374) and the second face (172; 272; 372) in use of the armature. The first face (170; 270; 370) is uninterrupted by the fluid communication means (178; 210; 310). The invention reduces the risk of cavitation damage during operation of the actuator. In one application, the actuator is used in a fluid pump (100; 200) for a selective catalytic reduction system.