Ventilation Dampers - Classification

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.

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:

q_l = q₁₀₀ (dp_l / 100)^1/2                           (1)

where

q_l = actual volume flow per m² valve area (m³/s / m²)

q₁₀₀ = volume flow at 100 Pa per m² valve area (m³/s / m²)

dp_l = actual pressure drop through the valve (Pa)

Temperature ^oC
K
^oF

Length m
km
in
ft
yards
miles
naut miles

Area m²
km²
in²
ft²
miles²
acres

Volume m³
liters
in³
ft³
us gal

Weight kg_f
N
lbf

Velocity m/s
km/h
ft/min
ft/s
mph
knots

Pressure Pa
bar
mm H₂O
kg/cm²
psi
inches H₂O

Flow m³/s
m³/h
US gpm
cfm