Foam in bag packaging system

A foam-in-place packaging system is disclosed that comprises a bag foamed of two sheets of flexible plastic film material sealed on all four sides by respective edge seals. A plurality of frangible seals are between the two sheets and define three separate interior cells in the bag. The frangible seals extend between the edge seals or between an edge seal and another frangible seal to thereby define a single cell bag when the frangible seals are broken. The cells separately contain a first and second foam precursor composition, and the bag includes means for permitting gases to vent from the bag as the foam precursors form foam while preventing foam or foam precursors from escaping from the bag. As a result, when the frangible seals are entirely broken, the separate cells foam a single interior cell in which the first and second foam precursors can mix thoroughly and react entirely to eliminate precursor residue and permit the resulting foam to expand properly and flow freely within the resulting single interior cell of the bag.