The present invention relates to a ventilating device for providing a zone (1) of clean air between the ventilating device and a workplace region (2), which ventilating device comprises air supply units (3) adapted to generating laminar air flows intended to constitute said clean air zone. The ventilating device comprises at least three air supply units (3) disposed in a closed pattern, and air stop and guide units (4) which prevent or hinder air with bacteria-bearing and other pollutant particles which surrounds the clean air zone (1) from being drawn in between the air supply units and into the clean air zone. The air stop and guide units (4) are also configured to guide parts of the air flows from adjoining air supply units (3) outwards from the centre of the clean air zone instead of towards the air supply units, and other parts of the air flows from adjoining air supply units in towards the centre of the clean air zone instead of towards the air supply units, thereby minimizing the increased downward velocity which occurs when the air flows from mutually adjacent air supply units meet in an uncontrolled manner.La présente invention concerne un dispositif de ventilation destiné à fournir une zone (1) dair pur entre le dispositif de ventilation et une région de travail (2), lequel dispositif de ventilation comprend des unités dalimentation en air (3) adaptées pour générer des flux dair laminaires destinés à constituer ladite zone dair pur. Le dispositif de ventilation comprend au moins trois unités dalimentation en air (3) disposées dans un motif fermé, et des unités darrêt et de guidage de lair (4) qui empêchent ou entravent laspiration de lair contenant des particules portant des bactéries ou polluantes autres qui entoure la zone dair pur (1) entre les unités dalimentation en air et dans la zone dair pur. Les unités darrêt et de guidage de lair (4) sont également configurées pour guider des parties des flux dair dunité dalimentation en air attenantes (3) vers l
