Twinflow STD

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Twinflow STD Centrifugal Twin Box Fan
Elta Select Product

Quick Facts

  • 7 standard sizes from 125mm to 500mm.
  • Air volume flow rates up to 1.89 m³/s.
  • Static pressures up to 1028 Pa.
  • Suitable for operating temperatures up to +60°C.
  • Available in EC.


  • Available for next day delivery with Elta Select

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Features & Benefits

Ease of installation

All models are designed for direct connection to standard diameter flexible or rigid circular ducting with 50 mm long spigots with EPDM rubber U shaped seals for ease of connection.

Material strength

A robust, yet lightweight unit with a galvanised sheet steel casing.


High efficiency low tonal noise backward curved centrifugal impellers are directly driven by an AC or EC external rotor motor, designed to be non-overloading and provide high performance characteristics. STD units are fitted with a non return damper for elimination of short circuiting of air within the casing.


Each unit is supplied with integral mounting brackets.

Design appeal

Ideal for roof spaces and / or where space is at a premium.

Quality assurance

All units are designed and manufactured with procedures as defined in BS EN ISO 9001: 2008.


Each STD 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. EPDM (Ethylene Propylene) rubber U shaped seals (being ozone and UV stable) are used to ensure a good seal back to the duct that is to be attached. Top & bottom access is provided as a standard feature to facilitate ease of maintenance and cleaning.


The twin range of units have an EC 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. Manufactured by Ziehl-Abegg providing increased reliability 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 ISO 14694 Grade G6.3 and directly driven by the motor to provide a smooth airflow through the unit.

Quality Management

Units are to be designed and manufactured with procedures as defined in BS EN ISO 9001:2008. All STD units are to be tested to ISO 5801:2007 (airside performance) and BS 848 Part 2:1985 (sound performance).
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