What is "LSZH" (Low Smoke Zero Halogen) material?

International Zone (English) OFSCN Knowledge Base (Public)
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Why is it mandatory to use patch cords with this type of jacket in subways or server rooms?

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The use of LSZH (Low Smoke Zero Halogen) jackets for fiber optic patch cords in enclosed spaces like subways and server rooms is primarily a critical safety requirement based on two physical and chemical factors during a fire: visibility and toxicity.

Here is the technical breakdown of why this material is mandatory in those environments:

1. Visibility (Low Smoke)

In confined spaces such as subway tunnels or high-density server rooms, smoke is often more dangerous than the fire itself.

  • Standard Jackets (PVC/PE): These materials produce thick, black, acrid smoke when burned, which can completely obscure exit signs and emergency lighting within seconds.
  • LSZH Property: When LSZH material is exposed to flame, it emits a very thin, light-colored smoke. This ensures that evacuation routes remain visible and fire rescue teams can locate the source of the fire quickly.

2. Toxicity and Corrosivity (Zero Halogen)

Halogens (such as Fluorine, Chlorine, Bromine, and Iodine) are highly effective fire retardants but are dangerous when they combust.

  • Toxic Gases: Traditional jackets like PVC contain chlorine. When burned, they release hydrogen chloride (HCl) gas. If inhaled, this gas turns into hydrochloric acid in the lungs, which is lethal.
  • Equipment Protection: In server rooms, the acidic gases produced by halogenated plastics will corrode sensitive electronic components, circuit boards, and metal connectors. LSZH materials do not contain these halogens, protecting both human life and expensive hardware from chemical damage.

OFSCN® Relevant Products

At Beijing Dacheng Everlight Technology Co., Ltd. (OFSCN), we utilize LSZH materials in various specialized fiber optic products intended for public infrastructure and industrial sensing. For example, our armored fiber optic cables used for FBG sensing often employ LSZH outer jackets to meet safety standards.

For more information on high-safety fiber optic cabling and FBG sensors, you can refer to:
OFSCN® Fiber Bragg Grating (FBG) Sensors and Cables
OFSCN® Special Optical Fibers and Cables