The in-line fan and silencer kits shall be of the WhisperJet Series  as supplied by Fantech Pty Ltd and be of the model numbers  shown on the schedule/drawings.  
Casings shall be manufactured from reinforced, injection  moulded, polypropylene plastic or epoxy coated steel.  Impellers shall be of mixed-flow design and manufactured  from injection moulded plastic or aluminium. They shall be  driven by a single-phase motor with manual-reset thermal  overload protection.  
The fan shall include an integral mounting foot, plug and lead and  specially designed support brackets to enable motor removal.  
The attenuators shall be of the CC Series circular M type as  designed by Fantech.  
All fans shall be fully tested to ISO5801:Part1.1997 for air flow and  BS848:Part 2:1985 for noise.