A VALVE AND A FLUID INJECTION SYSTEM

A valve comprising a housing (12) which has an exterior and which encloses an interior space, the housing being provided with an inlet port (28, fig 4) and an outlet port (29), both of which provide a conduit between the exterior and interior space of the housing, the valve further comprising a main valve seat (14) and a main valve member (16) which is located in the interior space of the valve housing, the main valve member being movable relative to the valve housing between a closed position in which it engages with the main valve seat and blocks flow of fluid between the inlet port and the outlet port, and an open position in which it is not engaged with the main valve seat and the inlet port is fluidly connected to the outlet port, the main valve member having a passage (24) which extends through the main valve member and provides a conduit for flow of fluid between the inlet port and the outlet port when the main valve member is in the open position, characterised in that the valve further comprises an auxiliary valve member (31) which is movable relative to the main valve member (16) between a closed position in which the auxiliary valve member blocks the passage thereby restricting flow of fluid along the passage, and an open position in which substantially unrestricted flow of fluid along the passage is permitted.