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Ventilation hygiene inspection, air duct cleaning equipment
| The Lifa Ventilation hygiene concept for circular and rectangular air supply and exhaust ducts and air handling units.
The concept consists of:
- criteria for cleaning and cleaning results
- methods for the visual evaluation of cleanness
- plans for cleaning
- optimal choice of the cleaning method
- advanced cleaning equipment and procedures
- quality assurance systems and education material
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Dirty supply air duct in a hospital
Air duct after cleaning |
DuctControl Maxi
A remote controlled video/digital camera system using a built-in mini tractor, which can be used for visually monitoring cleaning quality and microbial and other sampling methods and accessories.
Temperature measurement
Airflow measurement
Relative Humidity
Dust sampling
Instant display gas meters |
DuctControl Mini
A light hand cotrolled version for vertical ducts by which it is possible to survey cleaning needs, and check the quality of cleaning afterwards. |
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Special Cleaner 20
Electrically driven cleaning equipment with a wide range of accessories. Ideal for small ducts. |
Hydmaster
Powerful remote controlled hydraulically driven cleaning equipment with optional integration of video camera to the brush unit for real time control of cleaning quality. Hydmaster has a wide range of accessories |
HepaClean 4000
A low-pressure vacuuming unit that is adaptable to the maintenance opening or air valve site of the ventilation duct. The other valves are then covered. First the branches of the duct are cleaned using a rotary brush. Powerful airflow (10 – 20 ms/s) is needed to carry the loosened dirt into the collecting filter bag of the low pressure vacuum unit. Then the filtered exhaust air is conducted outside the building. A High Efficiency Particulate Air (HEPA) filter is used when there is not a possibility to conduct the air out of the facility. |
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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.
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Contaminant |
Organic dust
Bacteria
Fungi
Pollen
Algae
Plant parts & insects
Protozoa
Viruses |
Inorganic dust
Inorganic dust from ground
Coal dust
Flue dust
Soot
Heavy metals
Cement dust
Metal dust
Oil
Inorganic fibres
Lubricants & grease |
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Contaminant Source |
Organic nature
Industrial processes
Birds
Cooling towers
Water systems
Air humidifiers
Damp, wet materials
Excrement of arachnids
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Industrial traffic
The raw materials of sheet metal
Sound and heat insulation made of mineral fibre
Motors, gears and lubricants of fans |
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When accumulated |
Use of ventilation system.
Storage, transport and installation of ventilation equipment. |
Use of ventilation system.
Installation of ventilation system. |
Is our present knowledge enough to identify all the effects of ventilation system contaminants on people's living environment and health? For example, if bird droppings get into the ventilation system, they may contain Histoplasma and Cryptococcus fungi or other excrement-based fungi and bacteria. What is the risk to a hospital, if these fungi, when inhaled, lead to infections in patients with immunity deficiencies?
Regulations on cleaning ventilation ducts
Until now, ventilation systems have been cleaned voluntarily in Finland. The regulations affecting ventilation systems have been drawn up to cater for fire safety, and thus they seldom relate to incoming air ducts. On the other hand, the dust and grease that accumulate in the exhaust air ducts of buildings have been regarded as a fire risk, and their cleaning is therefore officially regulated.
According to the regulations of Finland's Ministry of Internal Affairs, ventilation equipment must be cleaned at least once per year for the sake of fire safety in the following types of premises:
- premises for professional food preparation
- industrial premises in which air ducts accumulate much flammable material
- premises where flammable liquids are used or made
Ventilation equipment must be inspected at no longer than 5-year intervals in:
nursing, service and penitentiary institutions
places of public accommodation and/or catering (hotels, restaurants, etc.)
Finland's Indoor Air Society has defined cleanliness classes for ventilation systems. Two classes, C1 and C2, are used for new ventilation systems. Class 1 signifies the best possible level that can be installed in work and residential premises, while class 2 is a level that meets the official requirements.
| The average concentration of dust in a ventilation system that is fit for sale or distribution may be no more than 1.0 g/m2 in class 1, and no more than 2.5 g/m2 in class 2. |
| Cleanliness class |
Maximum average dust concentration |
| C1 |
1,0 g/m2 |
| C2 |
2,5 g/m2 | |
| Incoming air ducts should be cleaned at 5-year intervals when the dust concentration is greater than 2.0 g/m2 in class 1, and greater than 5.0 g/m2 in class 2. |
| Cleanliness class |
Dust concentration greater than |
| C1 |
2,0 g/m2 |
| C2 |
5,0 g/m2 | | |
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