Abstract: A valve structure for cleaning purposes extends at least with part of its housing through a hole in a wall to be cleaned. Outlet nozzles in the housing extend so as to direct a cleaning medium substantially in parallel to or at a slight angle relative to the surface to be cleaned. The nozzles are so arranged that substantially a circle is covered by the resulting flow pattern. A valve closure is normally biassed into a nozzle closing position and may be lifted off the valve seat by the pressure of the cleaning medium flowing through the valve structure.