Rectangular

Another of our devices is the Non-return or back draft Damper which is used to prevent reverse flow.

The criteria here is that the device shall be self acting and not require an actuator, the resistance to forward flow shall be as low as possible, the device shall be robust enough to withstand reverse pressure, and the reverse leakage shall be very low. The issue to overcome is balancing the need for strength to absorb the reverse pressure load and low blade weight to minimize pressure loss under forward flow.

The Badger Damper design features a box section leading edge which gives high strength coupled with light weight and moves the centre of gravity towards the pivot axis. The under-cambered design means that the blade is aerodynamically lifted into the open position and not just blasted in to place with the consequent achievement of a low pressure drop.