Liberator MK4

The Colt Liberator MK4 range comprises axial powered smoke extraction fans designed to extract smoke and hot gases in the event of a fire. In addition, the Liberator is also used for day-to-day powered extract ventilation.


MK4 series axial smoke extraction fans move air in an axial direction. The fans are designed for S1 continuous operation (-20ºC and +55ºC) and S2 emergency operation. When in S2 emergency operation in areas with a fire hazard, the fans have been tested and approved for 300ºC/60min or 400ºC/120min. The smoke extraction fans are used in industrial, commercial and municipal buildings and meet the requirements of EN 12101-3.

They are tested and suitable for installation either inside or outside a smoke compartment (fire zone), and suited to either horizontal or vertical installation. The MK4 series fans are intended for installation within ventilation systems as supply or extract air units (does not apply to the Liberator TL/4 series).

Features and benefits

  • Low weight
  • Low current consumption
  • Dual function (smoke ventilation and day-to-day ventilation)
  • Can be controlled by a Colt frequency inverter
  • Tested in accordance with EN 12101-3

Available versions

Liberator L/4

Liberator L/4 (motor unit, consisting of a fan including mounting plate and protective grille) is suitable for both horizontal and vertical installation. It is complete with motor guard on the air intake side.

The ATEX version can also be used in hazardous areas classified as EX IIB T3 Gc (only valid for size 08).

Available in sizes 06 and 08, volume flows from 11800 m³/h to 32050 m³/h can be achieved (depending on the product configuration).

Liberator TL/4

A TL/4 Liberator comprises an L/4 motor unit and a T/4 closure unit where four non-return shutters close when the fan stops turning. These fans can be installed onto suitable flat upstands. The ATEX version can also be used in hazardous areas classified as EX IIB T3 Gc (only valid for size 08).

Liberator WL-Flap/4

A Liberator WL-Flap/4 comprises an L/4 motor unit and an insulated WL-Flap/4 shutter.

The shutter is motor controlled and is opened for smoke extraction and ventilation. Liberator WL-Flap/4 is suitable for both horizontal and vertical installation.

Liberator WL-FCO/4

A WL- FCO/4 Liberator comprises an L/4 motor unit and a Colt FCO shutter unit.

The FCO is equipped with a spring return motor and an automatic emergency fire release (thermal release at >93°C). The Liberator WL-FCO/4 is suitable for vertical (façade) installation.

Performance classes

In accordance with EN 12101-3

  • Resistance to fire:
    • F300 – 300°C / 60 min
    • F400 – 400°C / 120 min
  • Opening under wind load within a certain time period: Up to 20 seconds
  • Snow load: Up to SL 1000

Colt Liberator with a frequency inverter

Frequency inverter
Frequency inverter

When used in combination with the efficient Colt Liberator fans, the frequency inverter is certified according to EN 12101-3:2015 for use in smoke ventilation applications for the F300 and F400 classes.

In emergency mode, all thermal protection functions of the inverter are disabled. In the event of a fire, this ensures continuous operation of the fan until the frequency inverter or motor is no longer able to maintain operation. This means that no additional and costly bypass function is required for overriding the frequency inverter in the controller.

The input signal for the emergency mode can be activated by fire activation (voltage-free contact from manual release points and/or automatic releases), so that in the event of a fire the unit functions as long as possible in order to remove smoke or maintain the air quality in the building.

> More information about the frequency converter