Fuel system

摘要

A fuel system is described that comprises a pressure raising and shut-off valve (PRSOV) (22), and a control valve arrangement (40) operable to control a fuel pressure applied to a part of the PRSOV (22) urging the PRSOV (22) towards a closed position, wherein the control valve arrangement (40) is supplied with fuel at a pressure controlled by a variable fluid pressure potentiometer network (90) including a variable flow restrictor (94) which is variable in response to changes in the position occupied by the PRSOV (22).