Acoustic Centrifugal fans type SKRD, all with swing-out motor impeller unit, three phase. Simplifies maintenance & cleaning, with the addition of accoustic lining to acheive low noise levels. Silent rectangular fans for applications with specific noise level requirements. Very low noise levels acheived using 50mm thick rock wool insulation lining the casing. The rockwool lining has an abrasion resistant facing to protect the affects of the airstream over it.