Abstract: A flow valve operating by pressure differentials and by flow transfer means which regulate small flows of control. This valve is sensitive to small changes of pressure and resistant to great working pressures, having few components of a simple design. The valve of the invention basically consists in a rigid valve body with an opening for flow inlet and one opening for flow outlet, which are oriented in a substantially cross way to said flow opening. The body of the valve has a main cavity between the flow inlet and the flow outlet. A valve seat is in the limit of the main cavity and the flow inlet. In addition, the valve body has pipes for the inlet of the control flow and for the outlet of the control flow, which are associated with the flow transfer means for the control of the valve.