An auto purge for an intravenous contrast injector of the type having a motorwhich advances a plunger drive ram and configured for use with a pre-filled oruser-filled syringe containing an approximate known amount of air including aprocessor which causes the motor to move and a memory storing a predeterminedpurge stop point representative of the approximate known amount of air in thesyringe, the injector configured to automatically advance the plunger driveram an amount substantially equal to the predetermined purge stop pointrepresentative of the approximate known amount of air contained in the syringe.
