Fire Resistance Limit Test for Trough-Type Fire-Resistant Cable Trays

The fire resistance limit test for trough-type fire-resistant cable trays is performed in accordance with GB 29415-2013 Fire-resistant Cable Trays and GB/T 9978.1 Fire Resistance Test Method for Building Components. The core testing equipment is categorized into six systems: test furnace, temperature measurement, circuit integrity monitoring, loading and deformation measurement, pressure and environmental control, and auxiliary equipment.

1. Core Test Furnace (Essential) Fire resistance test furnace shall comply with the requirements of GB/T 9978.1 and be capable of heating in accordance with the standard fire time-temperature curve (ISO 834). The internal furnace temperature shall reach 950–1000℃ and accommodate cable tray specimens with a length of ≥4m. It adopts gas or electric heating, and is equipped with pressure control, smoke extraction, and safety interlock functions.
2. Temperature Measurement System Furnace internal thermocouples: Installed in compliance with standards to monitor furnace temperature and ensure conformity with the specified temperature-rise curve. Exposed-surface thermocouples: Mounted on the exterior of the cable tray to measure average and single-point temperature rises. Data acquisition instrument: Records temperature-time curves in real time with a measurement accuracy of ±1℃.
3. Circuit Integrity Monitoring (Critical) Test transformer: Three-phase star connection with a rated current of ≥3A. Fuses and circuits: Each phase is fitted with a 3A fast-acting fuse, and the neutral line with a 5A fuse, to simulate an actual cable circuit. On-off monitor: Detects circuit discontinuity in real time; fuse blowout shall be deemed a test failure.
4. Structural Integrity and Deformation Measurement Loading device: Hydraulic or mechanical type, applying a rated uniformly distributed load to simulate actual service conditions. Displacement sensor / laser micrometer: Measures deflection and deformation to determine whether collapse or cracking occurs. Crack observer / high-temperature camera: Inspects for the presence of penetrating cracks or flame penetration.
5. Pressure and Environmental Control Furnace pressure measurement system: Monitors internal furnace pressure to maintain compliance with standard negative pressure requirements. Smoke exhaust / ventilation system: Controls flue gas emissions to ensure test safety and data accuracy.
6. Auxiliary Equipment Specimen mounting brackets: Simulate field installation configurations (horizontal / vertical). Timing and control system: Provides automatic temperature control, timing, data storage, and test report generation. Safety protection devices: Include high-temperature protection, gas leakage alarm, and emergency fire-extinguishing systems.