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.