Cold splicing of fire-fighting plastic optical cables

Cold splicing of fire-fighting plastic optical cables uses mechanical connectors to join fibers without heat, ensuring signal integrity and compliance with fire safety standards.

Overview of Cold Splicing

Cold splicing, also known as mechanical splicing, joins two optical fibers using a connector rather than fusion or heat-based methods. The process relies on precise alignment of the fiber cores within a ferrule and connector body, which holds the fibers securely and maintains optical continuity . This method is particularly useful for plastic optical fibers (POF), which are more flexible and heat-sensitive than glass fibers .

Fire-Fighting Plastic Optical Cables

Fire-fighting or fire-resistant POF cables are designed to maintain circuit integrity under extreme conditions, such as high temperatures or fire, complying with standards like IEC 60331-25. These cables typically feature a PMMA core, polymer cladding, and a chlorinated polyethylene (PE) or LSZH jacket to resist fire, smoke, and mechanical damage . They are commonly used in tunnels, metro stations, petrochemical plants, and other critical safety environments .

Cold Splicing Procedure

1. Cable Preparation: Strip the outer jacket and cladding carefully to expose the fiber core. Clean the fiber to remove dust, grease, or debris, which can increase optical loss .
2. Insertion into Ferrule: Place each fiber into the ferrule of the mechanical connector. The ferrule ensures precise alignment of the fiber cores.
3. Securing the Connector: Insert the ferrule into the connector body, locking it in place to maintain alignment and mechanical stability.
4. Testing: Verify the splice using an optical power meter or optical time-domain reflectometer (OTDR) to ensure low insertion loss and minimal reflectance .

Advantages for Fire-Fighting Applications

• No heat required: Prevents damage to heat-sensitive POF cores and jackets.
• Field-friendly: Can be performed on-site without specialized fusion equipment.
• Maintains fire safety: Properly spliced cables retain their fire-resistant properties and circuit integrity for up to 90 minutes at 750°C, as required by IEC standards .
• Mechanical reliability: Provides sufficient strength for rugged environments, including armored or LSZH-jacketed cables .

Considerations

• Ensure the connector type is compatible with the POF diameter (commonly 1 mm core) and jacket material.
• Minimize fiber bending or stress during splicing to prevent signal loss.
• Use high-quality mechanical connectors designed for multimode POF to achieve optimal optical performance . Cold splicing is a practical and safe method for joining fire-fighting plastic optical cables, allowing rapid deployment and maintenance while preserving both optical performance and fire-resistance standards.