Ventilation hygiene investigation, HVAC air duct cleaning equipment
The Lifa Ventilation hygiene concept for circular and rectangular air supply and exhaust
ducts and HVAC air handling and air-conditioning units. Same cleaning and investigation
equipment is also used for industrial vent and pipe lines.
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
Dirty supply air duct in a hospital
Air duct after cleaning
Remote controlled video/digital camera system
using a built-in mini tractor by which it is
possible to survey cleaning needs and record the
quality of cleaning afterwards. It is also used
to reach the visual inspection to the critical
parts of ductwork where access doors canít be made.
Light and small hand controlled version for vertical
and very small ducts where the use of robot is not viable.
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Special Cleaner 20
Electrically driven cleaning machine with
a wide range of accessories. Ideal for small ducts.
Powerful remote controlled hydraulically driven cleaning machine with optional integration
of video camera to the brush unit for real time control of cleaning quality. Hydmaster has
a wide range of accessories, e.g. Y-gear for rotating 2 brushes in rectangular ducts.
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
(10Ė20 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
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
Plant parts & insects
Inorganic dust from ground
Lubricants & grease
Damp, wet materials
Excrement of arachnids
The raw materials of sheet metal
Sound and heat insulation made of mineral fibre
Motors, gears and lubricants of fans
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
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:
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.)
- premises for professional food preparation
- industrial premises in which air ducts accumulate much flammable material
- premises where flammable liquids are used or made
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
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.
||Maximum average dust concentration
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.
||Dust concentration greater than