Abstract: A flow control valve comprising a housing, in turn comprising a substance inlet opening and a substance outlet opening and a substance channel extending between the substance inlet and outlet openings. The valve further comprises: a piston carried by the housing and movable relative thereto; a first biasing member biasing the piston towards a first piston postion in which the piston seals the substance channel; a guide channel carried by the housing; and a valve actuator movable along and whithin the guide channel between first and second actuator positions.