accumulator comprises a fluid port assembly for communicating between a main housing of the accumulator and a connection arrangement of the accumulator an isolation valve arrangement is located within the fluid port assembly and is moveable between an open position for normal operation of the bladder accumulator and a closed position for isolating the bladder accumulator from a hydraulic system to which is it mounted wherein the valve arrangement is fixable in the open position application_number US 201013321358 A description a preferred embodiment of the present invention will now be described with particular reference fig1 and 2 the bladder accumulator of fig1 comprises a housing 2 within which is located a bladder 4 filled with an inert gas 6 such as nitrogen the upper end of the housing 2 and the upper end of the bladder 4 are formed with openings 8 into which is fitted a charging assembly 10 via which the gas 6 can be introduced into the bladder at the required pressure the housing 2 of the bladder accumulator has an opening at its lower end to which is fitted a fluid port assembly 12 the bladder accumulator is connectable to a hydraulic system via a connection arrangement which in this example is a flange 14 the flange 14 is fitted to the end of.