An insulated steel drum sound attenuator for a steel branch MVHR system – HSL Ltd Published 11 June 2021 at 2048 × 1532 in Difference between a branch and radial MVHR duct system – and which is better? An insulated steel drum sound attenuator for a steel branch MVHR system can be twice as “fat” as the duct it’s connected to. An insulated steel drum sound attenuator for a steel branch MVHR system ← Previous