Patent Number: 049845101
Section: summary

The present invention concerns a system for posting articles into a containment which is maintained at sub-atmospheric pressure. In particular the invention concerns a posting system with a port having a sphincter seal for minimising back diffusion through the port during a posting operation. FEATURES AND ASPECTS OF THE INVENTION According to the present invention a system for posting articles into a containment maintained at sub-atmospheric pressure comprises a posting port in the wall of the containment having a sphincter seal and a removable cover or lid, the sphincter seal being such as to engage articles posted through the port and to permit an inward air flow into the containment to oppose back-diffusion from the containment. Preferably, the sphincter seal comprises an annular assembly of inner and outer brush seals between which are sandwiched rings of resilient material. The outer annular brushes of the assembly serve to protect the resilient rings during posting operations. The lower annular brushes serve to support the resilient rings and help prevent permanent deformation. Both inner and outer brushes restrict the opening in the containment during posting operations.