Flexicon Flexible Conduit - Low Fire Hazard (LFH) Performance

By Chris Dodds on 8th September, 2014

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Flexicon Flexible Conduit - Low Fire Hazard (LFH) Performance

Flexicon Flexible Conduits

Low Fire Hazard (LFH)LSF (low smoke and fume) and LSOH (low smoke zero halogen)

Flexicon Flexible Conduit - Low Fire Hazard

Low Fire Hazard (LFH) conduit systems are becoming an increasing part of the specification in many cabling applications. Public buildings, retail outlets, high rise office blocks, hospitals and transport installations - these are just a few of the instances where Low Fire Hazard products may be demanded.

Low Fire Hazard systems are required to protect personnel and property in the event of a fire and may be demanded by specifiers, occupiers, fire services or even insurers.

See:  Flexicon Flexible Conduit - Low Fire Hazard (LFH) Performance

Flexicon Flexible  Low Fire Hazard (LFH) Performance Conduit

A Low Fire Hazard product has all of the following properties:

  • Highly flame retardant - prevents a fire or limits its development if one does start
  • Low smoke emission - to enable personnel to see their way to escape in the event of a fire
  • Low toxicity - to ensure personnel are not overcome during their escape in the event of a fire
  • Halogen free - rules out halogen acid gas emission and gives an indication of low smoke and low toxicity. Halogens are Fluorine, Chlorine, Bromine and Iodine

* All these four properties must be present to claim Low Fire Hazard (LFH)


Halogen free does not assure low smoke and low toxicity.

A low smoke and fume product may not be self-extinguishing let alone highly flame retardant. Ensure your supplier provides performance data on all four aspects of Low Fire Hazard performance.

Flexicon Flexible Conduit - LFHU Galvanised Steel LFH Low Fire Hazard Conduit


Flexicon Conduits and Fittings Tests and Standards

  • Flame Retardancy

Flame Retardancy BS EN IEC 61386 tests that the Flexicon conduits and fittings are self extinguishing. Vertical samples of conduit are subjected to a 1KW flame test. Flexicon fittings are subjected to a 750 degrees celsius glow wire test.

BS EN ISO 4589 determines the Limiting Oxygen Index (LOI) of a material. This is the percentage of oxygen in the air that would have to be present for the material to burn. Normal air contains 21% oxygen, BS 6853:1999, the UK code of practice for railway rolling stock requires 28% LOI for overground and 34% LOI for underground  passenger carriages.

UL 94 is a UL (Underwriters Laboratories) standard to assess the flammability of materials. Classifications are HB, V2, V1 and V0 in order of increasing flame retardancy. UL 95 HB allows horizontal burning up to a certain rate, UL 94 V0 is highly flame retardant.

  • Smoke Opacity

Smoke Opacity is evaluated by burning a known amount of product or material in a specified smoke chamber. A light is shone through the smoke and the loss in transmittance of light is measured over time.

  • Toxicity

Toxicity is evaluated by burning a sample of material under known conditions. The fumes are analysed to find the volume of each gas that is given off. The volume of each gas is multiplied by its toxicity potency to give a toxicity index for the material.

  • Low Fire Hazard Standards

All of the following standards assess flame retardancy, smoke emission and toxicity including halogen content.

BS6853 - UK rail rolling stock

LUL 1-085 - London Underground rolling stock and stations

NFF 16-101/2 - French rail rolling stock

DIN 5510 - German rail rolling stock

TS 45545 - New European rail rolling stock

AS/NZS 1530 - Australian/New Zealand rail rolling stock

Defence Standard 61-12 part 13 - UK Ministry of Defence


Flexicon Flexible Conduit Solutions and Fittings for Hazardous Area


  • Further Reading


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Category:  Flexible Conduit Cable Management

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