VDI 6022

Multi-floor and hygiene

As long as the multi-floor is installed, there will be a discussion about the extent to which this type of air routing is compatible with the hygiene requirements of ventilation systems.

Photo@Kemmer

The basis for compliance with current standards and regulations is the choice of materials.
According to DIN 1946, the inner surfaces of air ducts must be smooth and abrasion-resistant.
According to VDI 6022, “only those devices and system components may be used that do not emit any substances, fibers or odors that are hazardous to health and do not promote the growth of microorganisms”.
The hollow base plate, the core element of the Multiboden, is made of polystyrene.
In other words, the same material from which yoghurt pots are made.
Polystyrene contains no solvents, no plasticizers, does not release fibres and is insensitive to moisture.
That is the basis.

Measurements and expert opinions
On the occasion of the planning for the “Center for Integrative Medicine – CIM” in Koblenz, an existing facility with the Multiboden was examined by TÜV Rheinland in 2006 with regard to germ and pollutant contamination.
(Report no. 30001726)

The parameters germs, ozone and the number of 0.3 µm and 0.5 µm particles were analyzed.
Sampling and direct display of the particle sizes 0.3 μm and 0.5 μm was carried out using a laser particle counter.
The results of the microbiological tests showed that the values of the intake air were higher than those of the system air of the hollow floor.
The requirement that the system air should at least correspond to the outside air and the intake air was therefore fulfilled.
This project was subsequently approved by the “Institute for Hygiene and Infection Protection” of the Rhineland-Palatinate State Investigation Office.
The basis for this pioneering approval was the examination of the current state of an existing system.
But what needs to be considered when planning and installing new systems?
The transportation, storage and processing of pipes on the construction site play an important role in this context.
Simply masking duct parts during storage is not enough.
They often only become really dirty when subsequent trades leave their dirt behind.
This is why the air-conducting parts of the Multiboden must be sealed again after installation.
At the location of the air outlets to be installed later, a poly
styrene for adequate sealing of the system.
The air outlet is usually installed after or during the installation of the top floor.
Final cleaning of the outlet area can then be carried out by suction.

 

Compliance with VDI 6022 “Indoor air technology, indoor air quality”
The aim of the VDI 6022 “Indoor air technology, indoor air quality” series of guidelines is to Creation of healthy breathing air in buildings.
This series of guidelines therefore deals with the hygiene of ventilation systems and appliances.
The minimum objective is that the air discharged into the room is no worse than the air drawn in by the appliance or system.
This means that the ventilation technology itself must not be a source of contamination.

To ensure that the HVAC systems can guarantee the required physiologically favorable indoor climate and a hygienically perfect indoor air quality, the hygienic requirements of the systems must be met at all times.
There are specialized companies for the inspection and cleaning of ventilation and air conditioning systems that have trained personnel and the necessary special tools.

Inspection of the multibed
To check the hygiene status of air conditioning systems, VDI Guideline 6022 stipulates so-called hygiene inspections.
They should be carried out every three years – every two years for systems with humidifiers.
This is not an easy task in practice, as the air duct network is often difficult to access.
Nevertheless, there are ways of inspecting the system. About the removal of the floor air outlets.
With a sliding camera or a small inspection robot, you can even inspect longer sections.

Cleaning the multi-floor
For small ducts from 100 mm diameter, flexible shafts with rotating cleaning brushes are used in air conditioning systems.
Such devices are used in particular to clean connections from air diffusers to the duct network.
The more flexible such cleaning shafts are, the shorter their range.
The smallest shafts have a satisfactory range of approx. 5 to 10 meters. They have good gliding properties and can also clean oval or flat ducts.
However, at some point they can no longer be pushed, particularly in the case of deflections.
As all cleaning devices in ventilation technology can only loosen the dirt, an external unit is always required to collect the loosened dirt.
Such negative pressure devices or extraction units generate an air flow of 10 to 15 m/sec. This prevents loosened dirt from settling again.
A hygienic cleaning of such a system should always be rounded off with photo documentation.

Conclusion: The Multiboden complies with the requirements of VDI 6022 in terms of the materials used and the workmanship.
For safety and comfort, we recommend specialist companies for technical hygiene.