<p>A valve has a housing (20) having an inlet (30) and an outlet (32) and at least one closable access opening (38). The housing (20) defines a flow path along its interior from the inlet (30) to the outlet (32). A closure member (16) is located in the housing (20) and is movable between an operative position in which it is intersected by the flow path and an inoperative position in which it is clear of the flow path and projects out of the housing (20) via the access opening (38). A peripheral seal (54) on the closure member (16) engages the housing (20) to seal off the flow passage from the remainder of the interior of the housing (20) when the closure member (16) is in its operative position. A further seal (74) co-operates with the housing (20) for sealing off the flow passage from the access opening (38) when the closure member (16) is in its inoperative position.</p>
