LSF Low Smoke & Fume Conduit
Where escape routes, enclosed spaces and life-safety circuits are involved, the specification usually calls for a compound that produces less smoke and fume in a fire. The LSF range is the same conduit system in a specially formulated compound, supplied in grey.
Also searched as: LSF conduit, low smoke fume conduit, LSZH conduit, low smoke zero halogen, grey conduit
Performance
LSF heavy gauge conduit exceeds the requirements of the British Standards so that in the event of a fire, the emission of smoke and fume is much lower than standard PVC-U. Limiting oxygen index is 50% O₂, UL 94 rating is V-0, and Vicat softening point is 86°C — higher than the 80°C of the standard compound.
Full system, not just pipe
The LSF range is a complete parallel system: conduit, straight and expansion couplers, plain bends, adaptors, male bushes, saddles, the full nine-configuration circular box range, adaptable boxes to 380 × 280 × 90mm, surface and flush switch boxes, cover plates and flexible conduit. Mixing standard PVC-U fittings into an LSF installation defeats the specification.
A note on terminology
The terms "halogen free", "low smoke and fume" and "low acid-gas" do not on their own equate to low fire hazard. Rigid PVC-U is inherently flame retardant, has a low rate of smoke production in the critical early stages of a fire, chars and self-extinguishes, and does not produce flaming droplets. Specify against the tested properties, not the label.