2016/02/01 · Morton et al. defined three major sealing areas of a closed vial : first, the “land” seal formed between the vial sealing area and the rubber stopper closure flange (Fig. 3, no. 1); second, a “valve” seal along the inner vial neck and the rubber stopper plug (Fig. 3, no. 3); and third, a combination of the two seal types (Fig. 3, no. 2).