A machine for injecting liquids is disclosed including use of at least one air pump in fluid communication with at least one injection head having apertures for nozzles. High-pressure injectate flows from the air pump into the head, preferably through a threadlessly mounted filter located within the injection head. To further minimize contamination, fluid that enters the injection head will not contact any threading present in either the head or the nozzles. An air pressure regulator is included to ensure a steady stream of injectate of a desired pressure is delivered to an injection subject via each injection head and also helping to eliminate hesitation in delivery of the fluid by the air pump. Cleaning of the machine is simplified by moving sensitive components into a sealed enclosure, removing them from a wet working environment.
