A flow-control valve has a housing, a valve plate fixed in the housing and formed relative to a direction of flow through the valve with a flat upstream face and with an outlet port opening at the face, and a control plate fixed in the housing and formed relative to the flow direction with a flat downstream face riding on the valve-plate face and with a throughgoing inlet port opening at the face. This control plate is slidable on the valve plate for alignment of the ports and flow through the valve from the inlet port to the outlet port and for misalignment of the ports for restricted flow from the inlet port to the outlet port. A shield plate is fixed in the housing immediately upstream of the control plate and formed with an aperture aligned in the direction with and of generally the same shape as the port of the valve plate. Thus incoming flow will always be confined to a stream aligned with the outlet port of the valve plate.
