Controlled dilution flow in critical environments

A fluid delivery device (11, 11') configured to control a pattern of a flow of a fluid within a cleanroom (10), wherein the cleanroom comprises a clean area involving exposed activity subject to contamination , comprising the fluid supply (11, 11'): a first fluid supply port (111, 1110, 1111, 1112) configured to direct a first fluid supply jet (20) to direct a first flow of the fluid towards a center (O, O') of the clean area; another first fluid supply port (111, 1110, 1111, 1112) configured to direct another first fluid supply jet (20) to direct another first fluid flow toward the center of the clean area, wherein the first fluid supply port fluid supply is configured for a first section unit of the device and the other first fluid supply port is configured for a second section unit of the device; wherein the first fluid supply jet and the other first fluid supply jet are directable along a ceiling (114) of the cleanroom; and a second fluid port (111, 1110, 1111, 1112) configured to direct a second fluid supply jet (21) to direct a second flow of the fluid toward a perimeter (116) of the enclosure; another second fluid port configured to provide another second fluid supply jet to provide another second fluid jet towards the perimeter of the enclosure; wherein a pulse of the first fluid supply jet and a pulse of the second fluid supply jet can be arranged to be adjusted such that the center of the clean area is purged by the first flow and penetration of the second flow is prevented to the center of the clean area.