Disposable needle-free injection apparatus and method

A needle-free injector comprising:

• a cap including a first seal for sealing an injection orifice when engaged with an intradermal spacer disposed at an injection end of the injector, the seal being disposed at a distal end of a push-rod included with the cap for facilitating priming of the injector when engaged with a priming end of the injector;
• a push-rod engaging mechanism disposed at the priming end of the injector for receiving the push-rod;
• a gas cylinder for supplying pressurized gas for injecting, via the injection orifice, an injectate initially disposed within a storage chamber;
• and
• a sealing system for preventing the pressurized gas from ejecting the injectate from the injector prior to actuation via a slidable trigger plate, wherein the sealing system includes a second, radially displaceable seal disposed in a pressurized gas channel, and a corresponding recess in the slidable trigger plate for receiving the second seal as a result of actuation.