DGMS Guidelines – Two Independent Intake Airways for Each Ventilating District (CMR 2017 Reg. 153)

🌬️ DETAILED NOTES

1️⃣ Introduction

Proper ventilation is the lifeline of underground coal mines. It ensures supply of fresh air to all working districts and dilution/removal of gases, dust, and heat. As per Regulation 153(1) of the Coal Mines Regulations, 2017 (CMR 2017), “Every ventilating district shall be provided with at least two independent intake airways for ensuring adequate and reliable ventilation.” This regulation ensures that if one airway becomes blocked or inaccessible due to an accident or fall, air can still flow through the alternate route — maintaining life-saving ventilation.

2️⃣ Definition

Ventilating District: A section or district of a mine ventilated by a separate split of air from the main ventilating current.

Independent Intake Airways: Two or more airways carrying fresh air from the surface or main intakes to the working faces by separate routes, without any interconnection until the working place.

3️⃣ DGMS Objective

The purpose of requiring two independent intake airways is:

To maintain ventilation even in case of obstruction, explosion, or roof fall in one airway.
To provide alternative escapeways for workmen.
To enhance mine safety in gassy seams (Degree II & III).
To facilitate efficient air distribution and monitoring.

4️⃣ Relevant Legal Provisions

Regulation / Act	Description
CMR 2017 – Reg. 153(1)	Two independent intake airways for every ventilating district.
CMR 2017 – Reg. 153(2)	Separate return airway to discharge air directly into upcast shaft.
Reg. 153(3)	Each intake airway shall be connected to the surface through separate connections.
Mines Act, 1952 – Sec. 29	Mine ventilation and safety requirements.
DGMS Tech. Circular 02/2018	Guidelines for mine ventilation and air quantity measurement.

5️⃣ Layout and Design

In a typical underground layout, the two intake airways are:

Main Intake I (Fresh Air Route 1): Usually through a haulage road.
Main Intake II (Fresh Air Route 2): Often a man or material roadway.

Both lead to the same working district but are separated by barriers or solid coal to prevent short-circuiting. The return airway carries used air to the upcast shaft via a separate path.

6️⃣ Safety Benefits

Maintains ventilation in case of blockage in one airway.
Ensures continuous fresh air supply to working faces.
Provides alternate escape routes for workmen.
Reduces accumulation of gases (CH₄, CO, CO₂).
Increases reliability of the ventilation network.

7️⃣ Special Requirements in Gassy Mines

In Degree-II & Degree-III mines, the two intakes must be completely separate and clearly demarcated.
Air quantity, velocity, and methane concentration must be regularly monitored in both intakes.
DGMS requires ventilation plans showing both intakes and returns updated monthly.

⚡ QUICK ONE-LINERS

Regulation 153 – CMR 2017 mandates two intake airways.
Each ventilating district must have separate fresh air routes.
Purpose – redundancy and safety.
Applies to all underground coal mines.
Return airway must be separate.
One airway can be used for men/material, another for haulage.
Prevents short-circuiting of air.
Provides alternate escapeway.
Required even in development districts.
Must be shown in mine ventilation plan.

🧠 DESCRIPTIVE MODEL QUESTION & ANSWER

Q. Explain the DGMS requirement for providing two independent intake airways for every ventilating district as per Regulation 153 of CMR 2017. State its importance in mine ventilation safety.

Answer:
According to Regulation 153(1) of the Coal Mines Regulations, 2017, every ventilating district must have at least two independent intake airways to ensure reliable ventilation and safe working conditions. These two intakes provide alternative air routes so that if one airway is obstructed due to roof fall, explosion, or fire, the other can continue supplying fresh air to the working faces. The airways must be separated by solid coal or strata and should not interconnect before reaching the working place.

Importance: Maintains continuous air circulation; Provides alternate escapeway in emergencies; Reduces gas accumulation and explosion risk; Ensures compliance with DGMS safety standards.

Conclusion: Provision of two independent intake airways enhances mine safety by ensuring redundancy in ventilation, a key element of mine disaster prevention and rescue planning.

🎯 25 MCQs – Two Independent Intake Airways (Ventilation)

Q1. As per CMR 2017, each ventilating district must have:

Solution: Reg 153(1) explicitly states the requirement for at least two independent intake airways.

Q2. Relevant regulation:

Solution: Regulation 153 of CMR 2017 deals with the provision of intake and return airways.

Q3. Purpose of two airways:

Solution: Having two routes ensures ventilation continues even if one is blocked, enhancing reliability.

Q4. Independent intake airways carry:

Solution: Intake airways are designated for supplying fresh air from the surface to the workings.

Q5. Return air should pass through:

Solution: Regulation 153(2) requires a separate return airway to discharge used air.

Q6. Alternate escapeway provided by:

Solution: One of the key safety benefits of having two intakes is providing an alternative escape route.

Q7. DGMS circular on ventilation:

Solution: DGMS Tech Circular 02/2018 provides guidelines on mine ventilation practices and measurements.

Q8. Regulation 153(3) requires:

Solution: This clause ensures that the intake airways have independent connections right from the surface or main intake point.

Q9. Ventilating district means:

Solution: A ventilating district is defined by its independent split of the main airflow.

Q10. Mines Act ventilation provision:

Solution: Section 29 of the Mines Act, 1952, broadly covers the requirement for adequate ventilation.

Q11. Degree-III mines require:

Solution: Higher gassiness levels necessitate stricter controls, including complete separation of intake airways.

Q12. Air quantity to each district depends on:

Solution: Ventilation requirements are calculated based on factors like gas make, number of personnel, and machinery heat load.

Q13. Independent airways prevent:

Solution: Keeping intake routes separate prevents fresh air from bypassing the working faces and going directly to the return.

Q14. One airway may serve as:

Solution: It's common practice to use one intake for travel/transport and the other primarily for ventilation or haulage.

Q15. Both airways must:

Solution: To serve their purpose (ventilation redundancy and escape), both intakes must be kept clear.

Q16. Return air should not:

Solution: Mixing return (contaminated) air with intake (fresh) air is strictly prohibited to prevent recirculation.

Q17. Ventilation plan must show:

Solution: Ventilation plans must clearly depict the entire air circuit, including all intake and return airways.

Q18. Methane control achieved through:

Solution: Directing sufficient fresh air (split) to dilute methane is the primary ventilation control method.

Q19. Air velocity minimum (often cited guideline):

Solution: While specific values depend on location, 30 m/min is often cited as a minimum guideline for air velocity in working areas to ensure effective dilution and cooling. Check specific regulations.

Q20. Two intakes are separated by:

Solution: A substantial barrier of solid coal or strata is required to ensure the independence of the airways.

Q21. DGMS requires inspection of:

Solution: Regular inspection of the ventilation system, including airways, stoppings, and fans, is a core DGMS requirement.

Q22. Blockage in one airway leads to:

Solution: If one of the parallel intake paths is blocked, the total airflow to the district will decrease, although the second airway maintains some flow.

Q23. Ventilation in mines is measured by:

Solution: An anemometer is the standard instrument used to measure air velocity, which is then used to calculate air quantity.

Q24. Secondary airway serves as:

Solution: The second independent intake provides a crucial alternative escape route if the primary one becomes unusable.

Q25. Continuous ventilation ensures:

Solution: Maintaining adequate and continuous ventilation is fundamental to providing a safe atmosphere underground.

🔗 INTERNAL LINKING SUGGESTIONS

Related Topic	Read More On...
Ventilation Safety	Accidents Due to High Temperature
Safety Management	Integrated Safety Management Plan (SMP)
DGMS Syllabus	DGMS Exam Syllabus 2025 - CMR & MMR
CMR 2017	CMR 2017 Part 2 - Working & Supervision

🌬️ Master Mine Ventilation – CMR 2017 Regulation 153 with DGMS Notes!

Join Online Mining Exam – India’s 1st Online Mining Academy for:

Authentic DGMS Notes & Model Answers
25+ MCQs Per Topic
Expert Guidance for Coal & Metal First Class Exams

📞 Call/WhatsApp: 9971114020

Download Ventilation Notes & Practice 25 DGMS MCQs Now!

Online Mining Exam