Classification of Ventilation Dampers
Dampers in ventilation systems may be classified through function, construction or leakage class
Classification by Function
Dampers may be classified according their functional tasks in the ventilation system:
- adjustment
- closing, running
- closing, smoke
- closing, fire
- overpressure
- modulating
Classification by Construction
- plates
- membranes
Classification by Leakage Class
- based on BS EN 1751:1999
The leakage class determines the acceptable air leakage through the damper with a 100 Pa pressure difference.
- class 0 - No requirements
- class 1 - less than 0.2 m3/s per m2 valve area
- class 2 - less than 0.04 m3/s per m2 valve area
- class 3 - less than 0.008 m3/s per m2 valve area
- class 4 - less than 0.0015 m3/s per m2 valve area
The air flow rates through the dampers at 100 Pa are in general available from the manufacturers catalogs.
Function | Class | ||
---|---|---|---|
1 | 2 | 3 | |
Adjustment | x | ||
Closing, running | x | ||
Closing, smoke | x | ||
Closing, fire | x | ||
Overpressure | x | ||
Modulation | x |
Calculating Leakage Air Flow Rate through a Closed Damper
The leakage air flow through a closed damper can be calculated if the the difference pressure through the damper and the leakage air flow rate at 100 Pa (manufacturer data) through the damper is known:
ql = q100 (dpl / 100)1/2 (1)
where
ql = actual volume flow per m2 valve area (m3/s / m2)
q100 = volume flow at 100 Pa per m2 valve area (m3/s / m2)
dpl = actual pressure drop through the valve (Pa)
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