Abstract: The process of the invention concerns the manufacture of an interposed support of semipermeable microfiltration membranes, the support composed of a permeable mesh and a sealed border of elastomeric material. After deposition of an elastomeric film on a transfer support 2, the assembly which is obtained is cut into one or more elements 3 reconstituting the border; this or these elements 3 are applied on the mesh with their support(s) 2 and the elastomer is turned toward the mesh; then the mesh thus equipped is treated with pressure at a temperature of between 100.degree. and 150.degree. C. to cause the elastomer to penetrate into the mesh and to obtain a smooth border surface on each side of this mesh, allowing for a sealed joint. The product which is obtained is applied to the manufacture of microfiltration units, whether it has to do with ultrafiltration, with gas permeation or with hemodialysis.

Abstract: A pneumatic safety seal joint, made of elastomer, generally designed to be installed in a slot or groove, this joint having an inflatable internal volume under the pressure of a fluid, and an external seal surface. The joint has an internal volume with maximum internal width l and a maximum internal height H and has an internal sealed septum which divides the internal volume into two chambers, each with a means for pressurization. This internal septum is connected to the lateral walls of the joint such that the respective volumes of the two chambers are in a ratio between 0.9 and 1.1 and when l/H is between 1 and 2, the developed width L of this sealed septum is between 1.1 times and 1.4 times l, when l/H is between 2 and 8, the developed width L is such that 1.ltoreq.L.ltoreq.1.21. In case of the puncturing of one chamber the internal septum deforms and comes to press against the wall to be sealed, maintaining the seal.