Twinflow STDL

Twin Centrifugal Box Fan

  • 7 standard sizes from 125mm to 500mm
  • Air volume flow rates up to 1.740 m3/s
  • Static pressures up to 730 Pa
  • Suitable for operating temperatures up to +60°C
  • Redesigned casing to improve airflow and reduce specific fan powers
  • Auto Changeover Panel Included
  • Acoustically lined internally to reduce breakout noise levels
  • Low Specific Fan Powers
  • Configurable with optional demand control and spigot type
  • Available in EC
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Twinflow STDL fans are suitable for external mounting. The range incorporates advanced backward curved impellers.

Features and Benefits

Easy Installation

All models are designed for direct connection to standard diameter flexible or rigid circular ducting with long spigots.

Easy Commissioning

Integrated commissioning control allows single speed selection and also limits maximum speed if used with an external potentiometer.

Efficient Performance

High efficiency low tonal noise backward curved centrifugal impellers are directly driven by an EC external rotor motor, provide low specific fan powers and stepless speed control without tonal noise generation.


EC motors provide precise speed control via potentiometer, BMS or Elta DCV control. Reduced fan speeds can provide significant cost-savings through lower energy consumption in both mechanical energy of motors and also on the conditioning of replacement air.


Each STDL has a 12 month warranty.



Robust 1.2mm galvanised mild steel sheet casing. The casing is specially manufactured using integral motor mounting plates to provide additional rigidity for the casings. Each casing provides spigots to suit standard circular ducting.


EC external rotor motor fitted as standard. The IP44 motor contains sealed for life bearings. All motors are suitable for use in ambient air conditions up to +60°C.


High efficiency low tonal noise backward curved centrifugal impeller, dynamically balanced to ISO1940-1 and directly driven by the motor to provide a smooth airflow through the unit.

Duct Connection Options

Can be supplied with rectangular outlet & inlet spigots on request.

Electrical Connection Options

Electrical cable entry from either side for ease of electrical connection as standard (a terminal box pre-fitted to either side can be ordered).

Typical Applications

Hotels, Sports and Leisure
Hotels, Sports and Leisure
Education and Culture
Education and Culture

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