Coal mine hydraulic support systems require rubber hoses that meet strict standards for high pressure, flame resistance, anti-static properties, and wear resistance. Below are the selection criteria and common types:
(1) Steel Wire Reinforced Hydraulic Rubber Hose (MT/T 98-2006 Standard)
Structure:
Inner Layer: Nitrile Rubber (NBR), resistant to mineral oil and emulsion.
Reinforcement: 2~4 layers of high-tensile steel wire braid/wrap (pressure rating 16~42MPa).
Outer Layer: Flame-retardant Chloroprene Rubber (CR) or modified rubber with anti-static treatment.
Common Models:
Low-pressure fluid supply lines: 2SN type (16~21MPa, inner diameter Φ10~25mm).
High-pressure support control lines: 4SP type (35~42MPa, inner diameter Φ6~16mm).
(2) Ultra-High-Pressure Spiral Hose (ISO 1436/EN 856 Standard)
Applications: Large-height supports (working pressure >42MPa) or areas with frequent pressure pulses.
Features: 6-layer steel wire spiral construction, burst pressure up to 4× working pressure.
|
Parameter |
Technical Requirement |
Test Standard |
|---|---|---|
|
Flame Resistance |
Self-extinguishing within 10 sec after flame removal |
MT/T 98-2006 Annex A |
|
Anti-Static |
Surface resistance ≤1×10⁹Ω (prevents gas ignition) |
GB/T 9572 |
|
Pressure Rating |
No leakage at 1.5× working pressure for 5 min |
GB/T 5568 |
|
Pulse Durability |
≥200,000 cycles (±15% pressure fluctuation) |
ISO 6803 |
3. Key Considerations
Certification: Must have MA (Coal Mine Safety) certification—uncertified products are prohibited underground.
Fitting Compatibility: Prefer 24° cone seal (ISO 8434-3) or flange connections to avoid O-ring failure under high pressure.
Environmental Adaptability:
High-humidity mines: Outer layer should be anti-mold (e.g., with antimicrobial additives).
Low-temperature mines (-40°C): Use cold-resistant NBR or TPE materials.
LETONE Technology: A major manufacturer of MT/T 98-compliant hoses, specializing in coal mine support systems. Also supplies EN 856-standard hoses (requires additional MA certification). Leading in ultra-high-pressure spiral hose technology for large-height supports.
Monthly inspection: Check for cracks on the outer layer and leaks at fittings.
Pressure test every 6 months: Replace immediately if exposed wires or bulges are detected.
For specific model recommendations, provide working pressure and inner diameter requirements.
