Effect of Stress and Moisture Content on Permeability of Gas-Saturated Raw Coal

Figure 3

Schematic diagram of the testing apparatus. 1. Loading frame; 2. Axial loading hydro-cylinder; 3. Displacement sensor; 4. Stress sensor; 5. Servo hydraulic station; 6. Triaxial compression chamber; 6-1. Coal sample; 6-2. Heat shrinkable tube; 6-3. Circumferential extensometer; 6-4. Temperature sensor; 7. Constant-temperature oil bath; 8. Data acquisition system; 9. Gas cylinder; 10. Gas mass flow meter; 11. Vacuum pump;