Custom Hardware for Mine Safety Facilities

Bolt pull-out testing standards: 1) Sampling: Test at least 1 group (3 bolts) for every 300 bolts; 2) Method: Use a bolt pull-out tester for non-destructive testing; 3) Acceptance criteria: Pull-out force is not less than 90% of the design value, and displacement meets specification requirements; 4) Timing: Conduct after the anchoring agent has cured—generally 24 hours for resin bolts and 7 days for mortar bolts; 5) Records: Establish testing archives as a basis for project quality acceptance.

Principles for calculating U-shaped steel support spacing: 1) Determine based on surrounding rock pressure, typically 0.8-1.2m; 2) Use smaller values (0.8-1.0m) for weak rock, medium values (1.0-1.2m) for moderate rock, and larger values for stable rock; 3) Consider the support's bearing capacity to ensure the load on each support does not exceed its design capacity; 4) Increase density in special areas (e.g., faults, fracture zones); 5) Adjust dynamically based on field monitoring data to balance safety and economy.

Ventilation duct sealing requirements: 1) Sealing gaskets must be installed at flange connections, with a thickness of no less than 5mm; 2) Air leakage rate at joints shall not exceed 5%; 3) Flexible connectors should be made of flame-retardant and anti-static materials; 4) The inner wall of the duct should be smooth to reduce resistance loss; 5) Regular air leakage inspections should be conducted, and any leaks should be repaired promptly; 6) In high-gas mines, a double-layer sealing structure should be adopted to ensure explosion-proof safety.

Explosion-proof door installation specifications: 1) Location: Installed at key positions such as main intake and return airways, mining area entrances, etc.; 2) Opening direction: Should open towards the fresh airflow direction; 3) Strength: Capable of withstanding specified explosion pressure without damage; 4) Sealing: Maintains good sealing under normal conditions to prevent air leakage; 5) Interlocking: Interlocked with the monitoring system for automatic closure; 6) Identification: Equipped with clear safety signs and operating instructions; 7) Periodic inspection: Performance testing should be conducted at least once a year.

Common support monitoring methods: 1) Displacement monitoring: Using convergence meters and multi-point displacement meters to monitor roadway convergence and roof-to-floor displacement; 2) Stress monitoring: Using bolt dynamometers and pressure cells to monitor the stress state of supports; 3) Acoustic emission monitoring: Monitoring precursors of surrounding rock fracturing; 4) Video surveillance: Real-time observation of support deformation; 5) Microseismic monitoring: Monitoring the stability of large-scale surrounding rock; 6) Data analysis: Establishing an early warning mechanism to take timely measures when monitoring data exceeds thresholds.