Ventilation dampers

 Przepustnice wentylacyjne


Air dampers are an important component of ventilation systems. Depending on their actual function, dampers are divided into: regulating dampers, shutoff dampers and airtight dampers - which direct the air flow into the ventilation system.
Workmanship quality is the deciding factor for the damper’s insulation class. Detailed information on the requirements as regards damper insulation can be found in standard PN-EN 1751:2002 Building ventilation – End ventilation devices – Aerodynamic testing of regulating and shut-off dampers.


Damper insulation relates both to closing the air flow from the outside and inside the installation:


1. Insulation in relation to the external environment of the ventilation system:
Shows the amount of air leaking out of the duct to the environment at the connecting points as well as the amount of air taken inside the duct.
This characteristics is described by the insulation class: A, B, C and D
2. Insulation of a closed damper
Shows  the amount of air flowing through the closed damper in relation to the total closed duct surface. The leak amount determines the insulation class 0-4. For class 0 insulation, air-tightness is not required. Classes 0 and 1 are for regulating dampers. The highest insulation class 4 is reserved for airtight dampers.


Damper types –depending on surface type


•    Shutoff dampers in Alnor product offer include: DAS, DASL, DAS-PVC and DAS-CV 
Shutoff dampers have a full shutting blade with a 2 mm spacing at the duct edge.
Additional feature of DAS/ SASL dampers is the ideal blade shape and an overpressed mandrel space which improves the appearance and usable properties of the damper.
A big advantage are the reinforced damper surface with an overpressed cover.
Dampers starting at d-355 are also manufactured – with an additional 8 x 8 mandrel running lengthwise across the whole damper.

•    Airtight shutoff dampers – in Alnor product offer include among others: DAT and DATL
Airtight DATL dampers feature insulation class 4. 
The highest possible insulation class is attested by the report from testing conducted by the Institute of Heating Engineering and Air Preservation of the Kraków Polytechnic. 

The subject matter of the test includes:  Testing the internal insulation of the DATL-315 damper, as per PN-EN1751. The report is available on the website: www.alnor.com.pl.

•    Dampers with valve mechanism - DAOS, DAOSL and DSOQW-A
The butterfly/valve blade – lets the air go through in one direction only.
Tests of the DAOS/DAOSL dampers for insulation class indicate that they are close to Class 2  – very good result for dampers with no additional insulation  
and spacing at the lamellar connecting points.

•    Regulating dampers in Alnor product offer include: DAR and DARL
Regulating valves adjust the air flow in the ventilation to achieve desired values. The damper blade surfaces are designed so as to ensure a specific amount of air flow even when the damper is closed. The regulating surface allows about 30% of the air in the pipeline to go through.
DAP and DAPL pipelines are fitted with a regulating surface
which is often perforated. Its biggest advantage is the 30% air flow which is perfectly distributed in the duct cross-section. This leads to no air swirls and even pressure.

•    GBL Iris dampers – commonly known as the “Irises”
The iris surface allows for smooth air flow adjustment between 30 to 100% of opened surface. Additional socket ferrules allow to install a flow meter.
This damper type features a much lower noise level at a much higher air flow speed compared to standard dampers.

•    Multiblade dampers – DSQW, DSQW-A, DASQ and DASQL
In multiblade dampers, the shutoff element consists of a profile of up to 100 mm, moved by gears. 
They are used in larger duct diameters in which a much larger pressure and air flow would prevent opening or closing the damper mechanism. 
The DSQW-A damper can be used as insulation Class 2 and 4 – however this is only achievable with special, custom-made prefabricated components which are different from what is available as a standard in the Alnor Technical Catalog.

•    T-dampers – DATVL and DVTML 
T-dampers allow to smoothly and easily switch the air supply source.
It is often used in recuperator system where the air can be drawn, as required, from a wall mounted intake, or a ground heat exchanger. It saves time and allows for connecting an electrical control system.

•    Sliding dampers – GK and GKL
The sliding damper allows to clean the inside of the duct installation by means of brushes and robots. It slides up or down the plane – to open or close the duct.
Due to its construction, it takes up much more space outside the duct as its guiding surface protrudes outside the duct silhouette.

Damper adjustment mechanisms

Depending on your exact needs, available money and tools  we have many options to purchase or build the dampers.

•    KIT-DS-100-630 - Used in DAS, DASL, DAT, DARL

Consists of several components – images and information on how many are required to build a damper are freely available. 
One advantage is the possibility to use up to 50 mm insulation while ensuring smooth adjustment. Diameters starting from 400 mm are fitted with a KIT-DS-H handle for easy opening and closing of the mechanism. 
This mechanism, after a few alterations, is used in the DASM, which enables to install an electrical servomotor to control the damper.

•    KIT-DSKS - used in dampers: DASH and DARH
This mechanism features the simplest construction possible, heated directly via the casing – it is used when the mechanism is the most important characteristics to influence the damper price.
Depending on damper size, we use KIT-DSKS-145 for diameters from 80 to 160 mm, and KIT-DSKS-195 for diameters from 150 to 315 mm.

•    KIT-DSKKS
Alnor does not use this system in its dampers. It is very often used by companies manufacturing dampers – it’s a compromise between the KIT-DS-100-630 and KIT-DSKS mechanisms. 
It is also available in acid-proof version to be used in ventilation systems made exclusively of this material.

•    KIT-DS-PVC - Used in dampers: DAS-PVC  and DAR-PVC

This mechanism is used in dampers in diameters from 80 to 315 mm – the plastic mandrels have low resistance to mechanical loads. 
They are also used in small square dampers in size up to 300 x 300 mm. 
It’s a very nice and functional mechanism – it’s main advantages are: the possibility to use them in acid-proof or aluminum installations, very easy installation with just two holes to be screwed in the damper surface, and fastening by means of WGO screws. 
Perfect for smaller diameter dampers, even 50 mm – used in FLX-DAS and FLX-DAT dampers of the FLX-REKU system used to distribute air in floors or ceilings.

•    KIT-DS-CV  Used in damper models DAS-CV, DAR-CV, DAP-CV 
Features a 55 millimeter protrusion to attach insulation, however, the space under the mechanism should also be taken into account. Plastic mandrels allows to use it in dampers up to 315 mm in diameter. 
Its biggest advantage is the quick detachment of the handwheel - in about 3 seconds we are now able to install a servomotor.
It is very often used in designs where due to costs, manual dampers are used first, while servos and their controllers are installed later during actual use. 

•    KKS-2 Used to build steel and aluminum, square multiblade dampers DSQW and round dampers DASQ and DASQL. 
It is installed by sliding the “hands” into the PQ profile which acts as the damper frame. 
For full utilization of this mechanism, a 10 x 10 mm rod is required to be placed in the QKZ wheel and the ferrule, as well as inside the mechanism hands.
The dampers can be controlled manually or by using servos. 
The choice of damper is dictated by many factors – installation tightness, is it required to cut-off some sections of the installation when the rooms are not in use, or is it supposed to only adjust the air flow.
Also, the used mechanism determines the broader or narrower application as well as the difficulty of subsequent installation works – not to mention the final cost of the installation.

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Alnor Knowledge Base
Ventilation dampers
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