The valve (2) includes a main valve body (4) and an electromagnetic actuator (5). Valve body (4) defines an inlet chamber (65) with a radial inlet port (54) and an outlet chamber (67) with a radial outlet port (56). Valve means in the form of a generally tubular valve stem (6) projects from the valve body (2) into the actuator (5). The valve stem (6) is moved to open the valve by energising actuator (5). Two separate flow paths are defined between inlet chamber (65) and outlet chamber (67). The first is a direct annular passage (71) about the valve stem (6). The other flow path is via the interior (18) of hollow tubular valve stem (6) and an annular third chamber (70) defined by a valve insert (68). Interior passage (18) of valve stem (6) communicates respectively with inlet chamber (65) and third chamber (70) by respective rings of ports (16, 14) in the valve stem (6). The arrangement is such that the static pressure in the third chamber (70) communicated from inlet chamber (65) via ports (16), passage (18) and ports (14) acts on flange (20) and an adjacent portion of valve sealing ring (28) in the opposite direction to that of the pressure in inlet chamber (65) on flange (26) and sealing ring (30), whereby the static fluid pressure in the third chamber opposes the action on the valve stem (6) of the static fluid pressure in the inlet chamber, when the valve is closed. This arrangement is effective to reduce the force required to move the valve stem (6) when opening the valve (2) by energising actuator (5).
