Due to space constraint, backdraft dampers are frequently installed closed to fan discharge in ventilation duct system causing rattling noise and damage to the blade, blade linkage and its bearings.  Our engineers at OLS have produced a completely new version of the backdraft damper that is fail-proof and does not cause rattling noise under turbulence flow.

The OLS BD3000 backdraft damper is a twin blade design that pivot on ball-bearing or bronze bushes and does not response to air turbulence like most backdraft dampers.  Opening of the damper blade take place with very low pressure and air velocity, 10 Pa and 4 m/s respectively.   And air leakage rate in closed position is less than 0.05 m3/s/m2 at 1000 Pa pressure differential not achievable with normal backdraft damper.  This damper can be constructed to handle high velocity and pressure ventilation system.