Gas Testing Procedures | Indian Minerology

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Part 8: Gas Testing Procedures

Key Learning Objective: Execute complete gas testing workflow including pre-checks, sampling, recording, and statutory reporting (CMR 2017 Reg 118-122, Form V-24/V-25).

8.1 Pre-Testing Safety Checks

✅ 10-Point Pre-Test Checklist

Instrument Check
  • Battery >80%
  • Zero calibration (fresh air)
  • Span calibration (1.5% CH₄)
  • Alarm function test
  • Sensor response <30s
Personal Safety
  • Self-rescuer checked
  • Buddy system (2 men)
  • Communication radio
  • Escape route confirmed
  • Permit-to-work signed

8.2 Step-by-Step Gas Testing Procedure

🎯 Complete Testing Sequence

  1. Approach Point: From fresh air base, note time
  2. O₂ First: Verify >19.5% oxygen
  3. CH₄ Check: Roof (0.5m), mid, floor levels
  4. CO Scan: Breathing zone (1.6m height)
  5. Stabilize: 30 seconds per reading
  6. Record: 3 readings/location in Form V-24
  7. Action: CH₄>1% = Withdraw + ventilate
  8. Verify: Re-test after ventilation

8.3 Gas Testing Locations & Frequency

Location Frequency Priority Instrument Form
Working Face Pre-shift + hourly 1️⃣ Highest Multi-gas V-24
Return Airway 2 hourly 2️⃣ High Explosimeter V-24
Goaf Edge Continuous/remote 3️⃣ Critical Fixed monitor V-25
Intake Airway Daily 4️⃣ Routine Handheld V-24

8.4 Recording and Reporting Formats

📝 Form V-24: Gas Book Entry

DateTimeLocationCH₄%CO ppmO₂%ActionSignature
22/01/2614:30Face-15L0.82520.8OKRam Kumar
22/01/2615:45Goaf Edge1.34520.2EvacuateShift Incharge

Retention: 3 years | Language: English/Hindi

8.5 Follow-up Actions Based on Readings

🚨 ACTION MATRIX 🚨

CH₄ LevelCO LevelImmediate ActionFollow-up
0-1.0%0-50ppmContinue workHourly monitoring
1.0-1.25%50-100ppmStop hot work
Increase ventilation		15 min re-test
>1.25%>100ppmEVACUATE ALL
Manager approval		Continuous monitoring

8.6 Troubleshooting Common Issues

ProblemCauseSolution
Erratic CH₄ readings Moisture condensation Sensor dry-out + recalibrate
False CO alarm H₂S cross-sensitivity H₂S filter + zero in fresh air
No response Battery/sensor failure Spare instrument + log failure

⚠️ Exam Critical Procedures:

  • First gas test: Always O₂
  • Roof sampling distance: 0.5m
  • Form V-24 retention: 3 years
  • Evacuation limit: CH₄ 1.25%
  • Re-test interval: 15 min post-ventilation
  • Buddy system: Mandatory

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