Cleaning of ventilation and air conditioning systems
Basic hygiene-technological cleaning of ambient air duct systems
Ambient air technology systems and ducts are normally installed at an early stage of construction of a building. When rooms are being finished, other lots might develop a lot of dust (by preparing floors or dry construction works). As the ambient air systems are not operative at that stage but have a chimney-like effect, dirt will be drawn to the feeder lines. Visible sediments of construction dust can be found, especially on the duct bottoms. VDI 6022 requires that end devices of ambient air systems are to be installed in „clean buildings“. If this cannot be warranted, instruments and ducts have to be protected against introduction of dust. Often, this is neglected, or forgotten. Prior to taking any ambient air system into operation, it has to be verified that all parts in touch with the air flow have been thoroughly cleaned. The delivery of clean duct segments, interim storage in clean environments, assembly in dust free environment, and warranting that there is no more contamination until putting into operation is very expensive and troublesome. Often, final cleaning is required regardless of previous efforts and costs. The degree of contamination is highest in the throughputs and lines. This cannot be controlled by visual inspection of the end devices. Video inspection is advisable. Cleaning of such systems contaminated with construction dust corresponds to the processes for elimination of atmospheric contamination, and should be made on the supply air side from the end devices to the output. If duct parts are not washed before assembly, there might be traces of processing oils on the insides of the duct, and cleaning with suction or brushing will not be sufficient. Such oils have to be eliminated with a suitable solvent and wiped clean. Practise shows it is more reasonable to perform basic hygiene-technological cleaning only after completion of all construction activities. Qualified experts are able to clean the system parts and lines fully without necessity of disassembly. Systems for which DIN EN 12097 requires a high level of air duct cleanliness might require final disinfection after cleaning.