Multiflow SMB550/4-1AC

Mixed Flow Box Fan

  • Standard size 550mm
  • Air volume flow rates up to 1.476 m3/s
  • Static pressures up to 394 Pa
  • Suitable for operating temperatures up to +60℃
  • Available in AC


The unique and new blade geometry in this square, duct mounted, mixed flow fan offers increased airflow with smaller diameters.

Features and Benefits

Easy Installation

Lightweight construction with Ductmate flanges allowing easy installation.

Efficient Performance

High volume flow rates, high efficiency, low acoustic emissions due to special three-dimensional blade geometry with diagonal air discharge, reduced rotational tone.


A range of transformer voltage controllers can be used to provide five speed step control of single phase or three phase motors.

Energy saving

Backward-curved, aerofoil section blades provide high volume flow rates and high efficiencies.


Each SMB has a 12 month warranty.



The all metal casing shall be manufactured using pre-galvanised sheet steel suitably stiffened. Casings shall incorporate flange connections at each end. Motor supports shall be of pre-galvanised sheet steelconstruction and shall have an aerodynamic profile.


The single range of units shall have an AC external rotor motor fitted as standard. The motor contains sealed for life bearings. Thermal Class of motors to THCL 130 or 155 dependent on size. All motors are suitable for use in ambient air conditions up to +60 ℃. Electrical connection shall be via an IP55 terminal box mounted on the side for easy customer connection.


Impellers shall be made from high-performance compositematerial with 7 backward-curved, aerofoilsection blades.Three dimensional blade geometry with diagonal air discharge shall provide high efficiency and low acoustic emissions, directly driven by the motor to provide a smooth airflow through the unit.


Speed control shall be via stepped Transformer.

Quality Management

Units are to be designed and manufactured with procedures as defined in BS EN ISO 9001. All Multiflow SMB units are to be tested to ISO 5801 (airside performance) and BS 848 Part 2 (sound performance).

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