Non Return Flaps

These units are generally fitted on the outlet Air side of an installation, as an alternative to a motorised louvre, and are operated open purely by the outlet air velocity within the duct system. All units are purpose designed to suit clients individual requirements and the most requested specification is for pre-galvanised mild steel fully welded casing housing pre-galvanised mild steel blades mounted on solid stainless steel spindles running in nylon bushes. The maximum blade length based on face velocities of 1250 FPM (6.35m/sec) is 1300mm, but units having an internal casing width inexcess of this figure will have multiple banks of blades with mullions sited to cause the minimum restriction to airflow. Units suitable for much higher air velocities can be supplied but EAT must be advised accordingly before manufacturing commences. In the event that the units may be subjected to higher air velocities or turbulent air conditions it is advised that the blades be interlinked on their centre line so that they rise and fall in unison. As this action increases the pressure drop through the blades which cannot always be accomodated it may be neccessary in some cases to add counter balance weights. To cater for site conditions and global installations we can offer alternative constructions of 304 or 316l stainless steel: mill finish or marine grade aluminium: black or hot dip galvanised mildsteel and of course, as with inlet louvres, they can be supplied with a wet paint or powdercoat finish.

For more information on Non Return Flaps talk to Engineered Air Treatment Ltd