BACKGROUND STOCKS, INSTALLATIONS FOR MEDICAL INFORMATION PLANTS

摘要

PCT No. PCT/DE91/00896 Sec. 371 Date Aug. 7, 1992 Sec. 102(e) Date Aug. 7, 1992 PCT Filed Nov. 16, 1991 PCT Pub. No. WO92/10232 PCT Pub. Date Jun. 25, 1992.A nonreturn valve has a housing (1) provided with a central chamber (9) into which open an inlet channel (6) and an outlet channel (7) that may be separated by a sealing membrane (10) provided with a flow passage (18). The membrane (10) has a marginal part (16a) clamped in the housing (1), a central sealing part (16b) and a thinner annular wall (17) that links both parts (16a,16b). In order to obtain a nonreturn valve that has a reliable operation even at the smallest differential pressures, a central crater-like sealing formation (13,14), for example, is provided in the membrane (10). The inflow from the inlet channel (6) to the membrane (10) takes place outside the crater-like sealing structure (13,14) and the flow passage (18) of the membrane (10) is located within the crater-like sealing structure (13,14). The thinner annular wall (17) of the membrane (10), that generates a sealing pre-stress, has a shaped cross-section and its open junctures (17a,17b) adjacent to the marginal part and to the central sealing part (16b) of the membrane (10) are located at least approximately in the same plane, that coincides with the sealing plane, or is parallel thereto.