Patent ID: 6848480

Claim:
A process for filling a dual cartridge assembly, the process comprising the steps of: (a) providing a dual fluid cartridge assembly which includes an inner cartridge, an outer cartridge and a lower piston seal for sealing the inner cartridge and an upper piston seal for sealing the outer cartridge, both piston seals movable between an EMPTY position and a FILLED position, said dual fluid cartridge assembly having a vent open to atmosphere in said EMPTY position and closed when said lower piston seal is away from said EMPTY position; (b) moving said piston seal to said EMPTY position to allow trapped air in said inner cartridge to be vented to atmosphere; (c) filling said inner cartridge with a first fluid which causes said lower seal to move away from said EMPTY position and close the vent; and (d) filling the outer cartridge with a second fluid.