The Lifa Ventilation hygiene concept for circular and rectangular air supply and exhaust ducts and air handling units.
The concept consists of:
The ventilation system in general
Inspections of the cleanliness of ventilation ducts have normally been done by taking samples and making sensory inspections via the inspection hatches and at the incoming or outgoing air valves. The ducts have not normally been inspected throughout their whole length, and post-cleaning quality assurance inspections have normally been done from the inspection hatches only.
Lifa Air Ltd has done, and continues to do, much innovative development work to ensure that cleanliness inspections of the ventilation system are done thoroughly and well. Lifa Air Ltd has developed remote-controlled video camera robots and systems by which it is possible to survey cleaning needs, and check the quality of cleaning afterwards.
40 % of the contaminants in indoor air come with the incoming air via the ventilation system. The distances between filters in these incoming air ducts are often too long, and impure air may flow past them. Regardless of the filters in the ventilation system, some particulate contaminants from the outdoor air will enter the system and accumulate on the inner surfaces of the ventilation equipment or flow with the incoming air into the ventilated spaces themselves. And that’s not all. Contaminants may accumulate during the manufacture, transport, storage and installation of the ventilation equipment, and thus lower the quality of the incoming air. The contaminants originating from equipment manufacture include oil residues in the ducts. Equipment which is transported and stored in unprotected form may collect contaminants from the outdoor air and the ground. During installation, particulate contaminants such as cement dust and metal powder may also accumulate.
The dirt that collects in ventilation equipment and on duct walls and in various heat recovery, refrigerating, humidifying and air distribution equipment may act in humid conditions as a fertile soil for microbes.
The different kinds of indoor air problems derive mainly from a lack of regulations and maintenance, and partly from poor planning. Almost anything can be found in ventilation ducts that have not been cleaned – ranging from building waste to bird carcasses and excrement. Air inlets polluted by organic waste may become colonies of microbiological compounds which spread with the ventilation system throughout the whole building.
Ventilation system contaminants
Examples of various contaminants which are found in ventilation ducts or equipment and in cooling systems.
The particulate contaminants accumulated on the surfaces of ventilation systems, their sources and period of accumulation.