There is a common misapprehension that LSZH (or LSOH) and LSF cables are the same. This is totally incorrect. All respected and technically proficient distributors should be aware of the distinction between these two compounds.
Standard cables made of PVC and other compounds, when burnt, produce a number of chemicals including Hydrogen Chloride (HCI) which is highly toxic and when mixed with water HCI forms hydrochloric acid which is both toxic and corrosive. As much as 30% of the emissions from PVC can be HCI.
Low Smoke & Fume (LSF) cables are still manufactured using PVC compound. If they are marked as low smoke and fume it is due to the PVC compound being modified with various additives in order to reduce, but not eliminate, smoke and HCI emissions. It is interesting that there are no standards governing LSF cables and as a result some LSF cables have been found to emit HCI levels of in excess of 20% when burning.
Low Smoke, Zero Halogen (LSZH or LSOH) cables are not manufactured from PVC or modified versions of it and so produce very low levels of smoke and toxic fume and no acid gases. LSZH cables are governed by strict standards. In particular, BS EN 60754 stipulates that emissions of HCI by LSZH cables must not exceed 0.5%.
LSZH cables are often specified for indoors, especially in public areas, tunnels and underground rail networks.
So, when you’re next asked for LSF, pose the question- “Do you want LSF or LSZH?”
For more information contact your local Jointing Tech branch today www.jointingtech.co.uk
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