Valve assembly for controlling fluid flow

The present invention relates to a valve assembly for controlling fluid flow in a fluid flow regulator. The valve assembly comprises a deformable plug 1 e.g. of rubber, having a cylindrical body formed with a circumferential groove 5 and a pair of backing plates 2 and 3 located at either end of the plug 1. The plates 2 and 3 are bonded to the plug 1 and, in use, plate 2 is moved to stress the plug 1 and cause it to expand radially to restrict an annular clearance between the plug 1 and a valve seat (not shown) in which the plug 1 is located. This enables fluid flow through the clearance to be controlled. A flanged steel ring 4 is mounted on the backing plate 2 and a circular neck portion 10 of the plug 1 is located between the ring 4 and the plate 2, the portion being bonded to the plate 2. The ring 4, and especially the groove 5, serve to prevent or inhibit erosion of the plug surface in use.