🔹 1. Introduction

Fireline explosives are specially designed explosive systems used to create firebreaks or control lines during forest fire operations or surface mine fire hazards.
They help in quickly removing vegetation or creating trenches that stop the spread of fire.These systems are safe, non-electric, and deployable in rugged terrain — crucial for mining sites, forest regions, and rescue operations.

🔹 2. Purpose of Fireline Explosives

1. To clear vegetation and soil rapidly to prevent wildfire spread.
   
2. To construct control lines without mechanical dozers.
   
3. To safely remove combustible material in mines or forests.
   
4. To protect mine infrastructure near fire-prone areas.
   

🔹 3. Types of Fireline Explosives

Type	Composition	Remarks
PETN Cord (Primacord)	Pentaerythritol Tetranitrate	Used for rapid linear cutting
Water Gel Explosives	ANFO + Sensitizer	Safe and powerful
Emulsion Explosives	Ammonium Nitrate Emulsion	Used for wet conditions
Expanding Foam Line	Pyrotechnic-based	For controlled fireline creation

🔹 4. Initiation Systems

• EBW (Exploding Bridge Wire) Detonator: Uses electrical impulse to vaporize bridge wire; highly safe from stray current.
  
• Nonel Shock Tube System: Uses gas shock wave for transmission.
  
• Detonating Cord (PETN): High detonation velocity ~7,000 m/s; ensures uniform initiation.
  

🔹 5. Procedure of Fireline Blasting

1. Survey area and select fireline path.
   
2. Lay explosive line (cord or emulsion cartridges).
   
3. Connect to EBW/Nonel detonator system.
   
4. Evacuate personnel to minimum 300 m safe distance.
   
5. Fire using approved firing module.
   
6. Inspect and confirm trench or cleared area.
   

🔹 6. Safety Precautions

• Never use electric detonators during dry thunderstorms.
  
• Ensure all personnel behind natural cover before firing.
  
• Keep fire extinguishers and sand buckets available.
  
• Avoid using damaged PETN cords or wet emulsions.
  
• Follow DGMS (Tech Circular No. 1/2010) safety guidelines.
  

🧠25 DGMS-Style Objective Questions with Answers

1️⃣ Fireline explosives are primarily used for —

a) Mining excavation
b) Constructing firebreaks in forests or mines
c) Tunnel blasting
d) Avalanche control
e) Quarry fragmentation
✅ Answer: b) Constructing firebreaks in forests or mines
Solution: Fireline explosives create controlled firelines to stop the spread of wild or mine fires.

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2️⃣ The main explosive used in fireline operations is —

a) ANFO
b) PETN detonating cord
c) RDX booster
d) Black powder
e) TNT cast block
✅ Answer: b) PETN detonating cord
Solution: PETN (Pentaerythritol tetranitrate) cord is used for rapid, continuous linear cutting in fireline blasting.

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3️⃣ The detonation velocity of PETN cord is approximately —

a) 2,000 m/s
b) 5,000 m/s
c) 7,000 m/s
d) 9,000 m/s
e) 1,000 m/s
✅ Answer: c) 7,000 m/s
Solution: PETN detonating cords typically detonate at around 7 km/s, providing uniform linear detonation.

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4️⃣ EBW in EBW detonator stands for —

a) Electric Blasting Wire
b) Exploding Bridge Wire
c) Electrical Blasting Wave
d) Explosive Bridge Wall
e) Emergency Blasting Wire
✅ Answer: b) Exploding Bridge Wire
Solution: EBW detonators use a high-energy electrical pulse to vaporize a bridgewire, initiating the main explosive.

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5️⃣ EBW detonators are classified under —

a) Class A explosives
b) Class B detonators
c) Class C initiators
d) Class D fuses
e) Class E caps
✅ Answer: c) Class C initiators
Solution: EBW detonators belong to Class C — specialized electric initiators with low accidental initiation risk.

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6️⃣ Nonel systems transmit signal via —

a) Electric current
b) Gas pressure shock wave in plastic tube
c) Magnetic pulse
d) Hydraulic impulse
e) Fiber optic signal
✅ Answer: b) Gas pressure shock wave in plastic tube
Solution: Nonel tubes carry shock waves, not electric current, making them immune to static and RF hazards.

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7️⃣ Fireline explosives are used mainly by —

a) Civil engineers
b) Firefighting or forest protection departments
c) Quarry operators only
d) DGMS testing laboratories
e) Cement plant operators
✅ Answer: b) Firefighting or forest protection departments
Solution: Fireline explosives are applied to create rapid firebreaks during wildfire or mine fire emergencies.

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8️⃣ The purpose of fireline explosives is to —

a) Break rocks for mining
b) Cut a strip of vegetation and soil to stop a fire
c) Detonate large mine faces
d) Generate high seismic waves
e) Melt ice in avalanche areas
✅ Answer: b) Cut a strip of vegetation and soil to stop a fire
Solution: Firelines stop fire spread by removing combustible materials.

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9️⃣ The preferred initiation system for fireline blasting is —

a) Electric detonator
b) EBW or Nonel
c) Fuse and cap
d) Manual fire ignition
e) Chemical timer
✅ Answer: b) EBW or Nonel
Solution: EBW and Nonel provide safe, controlled initiation with immunity to static or stray current.

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🔟 Minimum recommended safety distance for fireline blasting is —

a) 100 m
b) 200 m
c) 300 m
d) 500 m
e) 1000 m
✅ Answer: c) 300 m
Solution: DGMS recommends a 300 m safety radius for small-scale line explosions.

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11️⃣ PETN detonating cord is also known as —

a) Safety fuse
b) Primacord
c) Fuse cord
d) Emulsion tube
e) Power cord
✅ Answer: b) Primacord
Solution: Primacord is the trade name for PETN-filled detonating cord.

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12️⃣ The major advantage of PETN cord over electric firing systems is —

a) Lower detonation velocity
b) Immunity to electrical hazards and simple linear layout
c) Complex circuit requirement
d) Very low efficiency
e) Dependence on current flow
✅ Answer: b) Immunity to electrical hazards and simple linear layout
Solution: PETN cords can operate safely even in lightning or static-prone zones.

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13️⃣ Which of the following explosive types is ideal for wet conditions?

a) ANFO
b) Water gel or emulsion explosive
c) TNT
d) RDX
e) Black powder
✅ Answer: b) Water gel or emulsion explosive
Solution: Water gels and emulsions remain stable and functional even in damp environments.

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14️⃣ The firing module for EBW detonators provides —

a) Constant low current
b) Short, high-energy pulse
c) Long-duration heating
d) Alternating current
e) Manual spark
✅ Answer: b) Short, high-energy pulse
Solution: EBW firing modules vaporize the bridgewire by discharging stored energy in a rapid pulse.

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15️⃣ Typical EBW detonator bridgewire resistance is —

a) 1–2 Ω
b) 10–20 Ω
c) 100–200 Ω
d) >1000 Ω
e) 0.1 Ω
✅ Answer: a) 1–2 Ω
Solution: EBW bridgewires have low resistance to allow rapid vaporization under high current.

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16️⃣ Which is NOT a component of a typical fireline explosive system?

a) PETN cord
b) EBW detonator
c) Detonating cord connectors
d) Booster charge for quarry bench
e) Nonel tube
✅ Answer: d) Booster charge for quarry bench
Solution: Fireline systems are designed for linear cuts, not deep-bench blasting.

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17️⃣ The main hazard during fireline blasting is —

a) Overbreak
b) Fire and heat from residual vegetation
c) Flyrock
d) Water seepage
e) Shockwave reflection
✅ Answer: b) Fire and heat from residual vegetation
Solution: Fireline explosions generate heat that can reignite debris if precautions aren’t taken.

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18️⃣ In fireline systems, explosives are laid —

a) In boreholes
b) On surface ground in continuous lines
c) Inside mine faces
d) Under heavy rock cover
e) In air gaps above vegetation
✅ Answer: b) On surface ground in continuous lines
Solution: Fireline cords are laid directly on the ground to clear strips through vegetation.

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19️⃣ Detonating cord can be connected in parallel using —

a) Electric switches
b) Detonating cord connectors or knots
c) Copper wire
d) Mechanical clamps only
e) Wooden plugs
✅ Answer: b) Detonating cord connectors or knots
Solution: Cord-to-cord connections must maintain explosive continuity using approved connectors or knots.

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20️⃣ The environmental advantage of fireline blasting is —

a) No dust emission
b) Reduced manual burning and less overall smoke
c) Loud noise generation
d) Increased CO gas output
e) Strong soil sterilization
✅ Answer: b) Reduced manual burning and less overall smoke
Solution: Controlled explosive lines create cleaner breaks with less long-term burning.

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21️⃣ During preparation, all detonating cords must be handled —

a) With metallic tools for easy cutting
b) Gently and cut with non-sparking tools
c) While burning small test sections nearby
d) Using heated knives
e) In open flames to soften
✅ Answer: b) Gently and cut with non-sparking tools
Solution: PETN cords are sensitive; use brass or plastic cutters only.

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22️⃣ Which factor most affects line uniformity during fireline explosions?

a) Detonating cord speed
b) Consistent laying height and straight alignment
c) Detonator resistance
d) Ambient light conditions
e) Wind direction
✅ Answer: b) Consistent laying height and straight alignment
Solution: Uniform placement ensures even detonation and clean trench formation.

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23️⃣ Before initiation, personnel should —

a) Move at least 300 m behind cover
b) Stand beside cord for visual verification
c) Use radios near detonation area
d) Touch detonator wires to check current
e) Stand on elevated positions to film blast
✅ Answer: a) Move at least 300 m behind cover
Solution: Safe distance prevents injury from debris or shock.

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24️⃣ Fireline explosives are categorized by DGMS as —

a) Controlled surface blasting methods
b) Deep-mine blasting techniques
c) Electrical fuse-based detonations
d) Secondary initiation systems
e) Fireworks systems
✅ Answer: a) Controlled surface blasting methods
Solution: DGMS classifies them under controlled surface blasting for fire control.

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25️⃣ The best time to perform fireline blasting is —

a) During heavy rain
b) When wind is moderate and humidity is high
c) On extremely dry and windy days
d) At noon in hot sunlight
e) During thunderstorms
✅ Answer: b) When wind is moderate and humidity is high
Solution: Moderate weather reduces secondary fires and aids safety.

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🔚 Quick Summary
Main explosive: PETN cord
Initiation: EBW or Nonel system
Application: Forest/mine fire control
Safe distance: ≥ 300 m

                           🔚 8. Conclusion

Fireline explosives represent a safe, quick, and effective technique for wildfire prevention and surface fire control. Their use in open mines and forest areas ensures better safety and environmental control. DGMS emphasizes proper handling, initiation safety, and correct distance maintenance during such operations.

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