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Fire Rated Ducts

Fenland Fireduct

Approximately 85% of deaths in fire situations are caused by smoke inhalation. Non- fire resisting ductwork systems can be responsible for allowing the initial spread of fire between compartments, and by allowing the rapid spread of smoke and decomposition products. The correct use of fire resistant ductwork will maintain fire compartmentation and assist in the safe dispersal of smoke and hazardous fumes.The Fenland Fireduct system is an augmented ductwork construction utilizing the latest manufacturing echniques to which an intumescent coating is factory applied. As the coating is spray applied, this allows the ductwork system to be manufactured in any cross sectional shape to suit the application, producing a flanged single skin Fire Rated Ductwork system giving Stability and Integrity of up to 4 hours.

Leminar Air Conditioning Industries is the sole manufacturing licensee for Fenland Fireduct system – UK for Qatar. All Leminar personnel are trained by FFC-UK and Fenland Fire Contracts (UK) experts for its applications and constructional requirements.

The Fenland Fireduct System complies with the requirements of Method 3 of BS 5588 part 9: 1989 & Method 3 (clause : of BS 9999:2008, has been fully tested in accordance with BS 476 part 24: 1987 (ISO 6944: 1985) for 4 hours stability and integrity for Type A ducts (Fire outside) and 3 hours stability, integrity and 2 hours insulation for Type B ducts (fire inside).

The Fenland Fireduct System has been tested and assessed by the BRE Centre for Fire Resistance (formerly the Loss Prevention Council) as being suitable for use as, “a Fire Rated Ventilation Duct, a Smoke Extract/Outlet Duct or a Kitchen Extract Duct.”

The Fenland Fireduct System is assessed by Warringtonfire Exova and listed in their mideast scheme.

  • Up to 4 hours- stability, integrity and insulation.Typical for escape lobby ventilation and staircase pressurisation systems.
  • Up to 3 hours- stability, integrity and 2 hours insulation.Typical for kitchen extract, smoke extract and other re rated systems.


In accordance with BS 476 Part 24 : 1987 for the fire resistance of ventilation ductwork which is expressed in minutes of duration of heating in accordance with the ISO 834 : 1985 (Cellulosic – Standard Time/Temperature Curve) until failure occurs to one or more
of the criterion :-

Stability : Stability failure shall be deemed to have occurred in duct ‘A’ within the furnace and in ducts ‘A’and ‘B’ outside the furnace when the duct no longer fulfils it`s intended function. (For smoke outlet ducts stability failure will also be deemed to have occurred when there is any restriction of the cross sectional area of the duct to 75% or less of its original area).

Integrity : The presence and formation of any cracks, holes or other openings outside the furnace through which flames or hot gases can pass.

Insulation : Insulation failure shall be deemed to have occurred when the temperature rise above initial ambient on the unexposed surface of the duct outside the furnace exceeds either:

  • 140 °C as an average value above ambient.
  • 180 °C as a maximum value above ambient.

For a Kitchen extract duct (Type A) these temperature limits also apply to the inside surface of the duct within the furnace.

Reasons to choose Leminar

  • The FFC-UK fire rated duct system is tested to the most stringent international standards and certified by independent laboratories.
  • FFC-UK Duct system has been approved by Qatar Civil defence.
  • FFC-UK Duct system has been approved by all the major MEP consultants / Clients and have been used on various prestigious projects.
  • Leminar is one and the only company in the region which is having the facility of duct fabrication and fire rated coating application all under one roof. This ensures a stringent quality control, easy co-ordination due to single point responsibility and faster deliveries.
  • All the raw materials like the FFC 2S0 coating, FFC Intumescent gaskets and FFC Intumescent Acrylic sealant are manufactured and imported from the UK.
  • Leminar strictly follows the method statement for fabrication of the ducts as defined by FFC-UK for duct fabrication to ensure compliance with test standards.
  • Leminar shall assist with any technical matter that may arise during installation at site.
  • Leminar’s technical team has been fully trained and authorised by Fenland Fire Contracts (UK) to issue a Certificate of Conformity upon satisfactory inspection of the installed ducts by MEP contractors.
  • FFC fire rated duct system will provide 2 hours fire rating for insulation criteria for smoke extract ducts experiencing temperatures of up to 350 degrees celsius. FFC 250 fire coating itself will provide 2 hours insulation resistance and hence any external insulation is not essential in this case. This will assist in keeping the expensive insulation costs to a minimum as well as be suitable for places where there are space constraints.

Example Specification

The Smoke Extract ductwork should be constructed in accordance with the Fenland Fire Duct specification for Fire Resistant ductwork, to provide 120 Minutes Stability, 120 Minutes Integrity and 120 Minutes Insulation (or 120 Minutes fire Insulation to suit a smoke temperature of 300 °C) when tested to the requirements of BS476 part 24 : 1987 by a recognised NAMAS/UKAS Accredited laboratory.

The ductwork systems should be manufactured and installed in accordance with BS5588 part 9 : 1999, and be capable of providing type ‘B’ fire containment. Under normal non-fire operating conditions the ductwork should conform to the class C pressure/leakage classification of the current HVCA DW/144 specification for sheet.

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