Damper Leakage Rating – Definition and Classification
Damper Leakage ratings of the dampers are established at a minimum differential pressure of 4 in. WC, across the closed damper. Leakage rates may also be established at higher differential pressures, in increments of 2 inWC.
Leakage ratings for smoke dampers are identified as Class Designation I, II or III as shown in the following table.
|Table 1: Maximum Allowed Leakage (CFM / Ft2)|
|Class||4 InWC||6 InWC||8 InWC||10 InWC||12 InWC|
Leakage ratings of smoke dampers are determined at elevated temperatures. The elevated temperatures are in increments of 100°F with the minimum temperature being 250°F.
Smoke Damper Leakage ratings are established based on test conditions using heated air.
Classified dampers are marked with respect to the Leakage Class at elevated test temperature.
COMBINATION FIRE AND SMOKE DAMPERS
Combination fire and smoke dampers are intended for use in locations that are designated as both fire barriers and smoke barriers. These products can also be described as combination fire/smoke dampers as defined by the International Building Code (IBC) 2000.
Combination fire and smoke dampers are evaluated for both a fire resistance rating of 1-1/2 hrs or 3 hrs, and thus a leakage rating as defined under “SMOKE DAMPERS.”
Damper Leakage rating of combination fire and smoke dampers are determined at an elevated temperature 250°F or 350°F, based on test conditions using heated air.