A method of manufacturing a flexible, rupturable container 121 for propellant for a syringe comprising the steps of: sealing a first sheet of material 124a to a second sheet of material 124b to form a lower seal 125a and two side seals 125b, 125c； sealing a propellant dispensing apparatus 410 with the central volume to deposit propellant； and then sealing the first sheet to the second sheet to form an upper seal 125d to form a propellant container. The sealing may be done by a set of four side rollers 412 and a sealing element (408b, see figure 14A) with a temporary clamp means 408a either side. Other methods of frangible pouch manufacture include sealing the ends of a tube 224 at 225a and 225b, forming an opening 304 in the tube through which to dispense propellant, and forming a second upper seal 225c (see figure 13A-13D)； or cutting a container 128 to form an opening 130, depositing propellant in the container, temporarily clamping 127and then sealing 125d the container (see figure 15A-15E).
