An injector (20) that may be used to deliver radiographic contrast media and/or flushing solution into a patient's vascular system for the purposes such as obtaining enhanced diagnostic x-ray images. The injector includes the following features: (1) a syringe mount (26) for attachment of a syringe (28) to the injector (20)； (2) display (34) and controls (90) for volume and flow rates； (3) automatic limiting of the operating pressure of the injector (20) as determined by the selection of a flow rate； (4) a syringe cradle (48) having a warming capability； (5) a purge/retract trigger (36) for control of the injection procedure having intuitive direction (i.e., forward for injecting, reverse for filing), non-contact control transmission through the housing of an injector (20) for an improved seal integrity, a speed lock, and/or the ability to change the concentration and/or flow rate of media or other fluid during an injection procedure； (6) a switch to determine when the drive ram (46) is in a "home" position； (7) a "soft" on/off power switch separate from the injector； and (8) a structure to prevent rotation of the drive ram (46) about its axis of symmetry (76). Additionally, the injector system includes software for the control of various components.
