Airtight, seamed casing made from galvanised steel.
Leakage rate compliant with tightness class C, according to EN 12237:2003.
Voltage controllable external rotor motors.
Radial impeller with backward curved blades.
Speed controllable via stepless thyristor or 5-step transformer.
Integrated thermal contacts with manual reset in accordance with EN60335-2-80 (sizes 100 M and 125 M have integrated thermal protection).