Why are jumpers with this kind of jacket required in subway stations or machine rooms?
In subway stations (enclosed/semi-enclosed public safety spaces) and equipment rooms (high-density precision electronic equipment environments), the mandatory use of LSZH (Low Smoke Zero Halogen) jumper cables or optical cables is based on strict engineering considerations from two perspectives: fire safety (personnel survival rate) and equipment asset protection (corrosion prevention and secondary disaster mitigation):
1. Enclosed Spaces such as Subway Stations: Ensuring Personnel Life Safety
- Avoiding Toxic Acidic Gas Generation: Traditional jacketing materials like polyvinyl chloride (PVC) or fluoroplastics contain halogen elements (e.g., chlorine, fluorine). When these materials burn during a fire, they release large amounts of gaseous hydrogen halides (such as hydrogen chloride, \text{HCl}). Upon contact with moisture in the respiratory tract and eyes, these gases instantly form strong acids, causing severe burns to the respiratory tract, suffocation, and even death for those who inhale them. LSZH materials, however, do not contain halogens and do not produce such toxic acidic fumes when heated or burned.
- Extremely Low Smoke Density to Ensure Escape Visibility: The incomplete combustion of traditional plastics during a fire produces extremely dense black smoke, rapidly reducing visibility to zero in enclosed spaces (like underground platforms, tunnels, and narrow passages), severely hindering personnel evacuation and firefighting rescue efforts. LSZH materials use inorganic flame retardants such as aluminum hydroxide (\,\text{Al(OH)}_3\,) or magnesium hydroxide (\,\text{Mg(OH)}_2\,). When heated, they primarily release water vapor (\,\text{H}_2\text{O}\,) and form a protective carbonized layer, producing very little smoke (and it’s light-colored). This maximizes visibility in escape routes.
2. Equipment Rooms and Data Centers: Protecting High-Value Precision Electronic Equipment
- Preventing “Secondary Corrosion” Caused by Acidic Gases: Even in small fires with low localized temperatures, the \text{HCl} gas released from burning PVC optical cables can quickly spread throughout the equipment room via the precision air conditioning system. These acidic gases can adhere to metal contacts, gold fingers, and printed circuit board (PCB) copper traces on servers, switches, and optical modules, causing severe chemical corrosion (i.e., secondary corrosion hazard) and rendering the entire piece of equipment irreparable. The non-corrosive gases produced by LSZH materials during combustion protect these high-value precision devices from acid damage.
- Preventing Short Circuits from Conductive Smoke Particles: The charred carbon particles generated from the combustion of traditional jacketing are conductive. If they drift and deposit on precision electronic components, they can cause circuit short circuits. LSZH combustion residues are primarily inorganic, non-conductive ash, offering significantly higher electrical safety.
Product Series Explanation from Dacheng Yongsheng (OFSCN®)
Standard low-voltage/indoor LSZH optical fiber patch cords are common network cabling consumables and are not part of Dacheng Yongsheng (OFSCN®)'s core product series.
To address more demanding special industrial environments requiring extremely high physical protection and fire resistance (such as extreme temperatures, high external pressure, or high tensile strength requirements), Dacheng Yongsheng (OFSCN®) has developed the following series of highly reliable special optical fiber patch cords with a seamless stainless steel armored structure. These products achieve superior physical isolation and fire resistance not by relying on plastic jacketing for flame retardancy, but by utilizing seamless steel tubing:
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OFSCN® 120℃ Fiber Optic Patch Cord
- Key Parameters: Comprises fiber optic connectors (FC, ST; PC or APC are acceptable), 0.9\text{mm} seamless stainless steel tubing, and 120^\circ\text{C} polyacrylate optical fibers. Its operating temperature range is from -40^\circ\text{C} to 120^\circ\text{C}, with excellent tensile strength (\,\u003e150\text{N}\,) and compressive strength (\,\u003e240\text{MPa}\,) characteristics.
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OFSCN® 200℃ Fiber Optic Patch Cord
- Key Parameters: Uses seamless stainless steel tubing with special 200^\circ\text{C} polyimide optical fibers, enabling stable operation in extreme ambient temperatures ranging from -200^\circ\text{C} to 200^\circ\text{C}. This fundamentally eliminates the risk of standard plastic jacketing melting or producing smoke at high temperatures.
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OFSCN® 300℃ Fiber Optic Patch Cord
- Key Parameters: Features a high-temperature, thin-diameter, single-mode/multi-mode polyimide optical fiber encapsulated in seamless stainless steel armored tubing, supporting reliable operation in extreme low and high temperatures ranging from -270^\circ\text{C} to 300^\circ\text{C}.
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