Abstract: A method and an installation for conserving and/or dispensing a liquid or semi-liquid substance (P) released in a deformable flexible bag (s). The substance may be extracted from the bag by actuating and appropriate drawing-off dust (12), with the substance being drawn off via the duct (50) which remains closed so long as the bag (s) is not in place in a conservation and/or dispensing apparatus. While the bag is in the apparatus, and so long as the bag is not entirely empty, the substance is circulated by a pump round a closed loop circuit which extends in part outside the bag, with the circuit being set up when the bag (s) is put into place in the conservation and/or dispensing apparatus.