Abstract: A novel seal arrangement is provided for use in processing apparatus of the type including a partition for separating zones of relatively high and low pressures. At least one aperture is provided in such partition, the aperture having a wall. A processing unit (such as a hydrocyclone) has a portion thereof located in such aperture so that an annular region is defined between such unit and the aperture wall. An annular seal of resiliently deformable material is located in this annular region and provides a seal between the above noted zones. This seal is of cup-shaped form and includes an annular outer seal lip which is radially spaced form the processing unit. This seal outer lip is connected to the remainder of the seal via an end wall. The seal outer lip has inner and outer surfaces and a free annular edge remote from the end wall.

Abstract: A hydrocyclone heavy fraction outlet unplugging grommet for use in hydrocyclone systems is described. The grommet is self-sealing under the pressures encountered in use and will effectively seal around a relatively large water nozzle inserted therethrough in the course of an unplugging operation.