1950s U.S. ARMY DEMOLITION ELECTRIC PRIMER TRAINING FILM 32454

Introduction

This tutorial provides a comprehensive guide on the use of electric primers in military demolition, based on a training film from the 1950s U.S. Army. It covers the types of explosive charges and caps, the priming process, and safety precautions necessary for effective demolition work. Understanding these steps is crucial for anyone involved in demolition operations.

Chapter 1: Understanding Explosives

• Most demolition work in the Army is conducted using insensitive explosives.
• Common applications include:
  • Land clearing operations
  • Ditching
  • Cratering

Chapter 2: Main Explosive Charges

• To detonate a main charge, a smaller charge known as a blasting cap is required.
• There are two types of blasting caps:
  • Non-electric: Uses a time fuse and recommended for combat operations.
  • Electric: Requires more equipment and is suited for simultaneous detonation of multiple charges.

Chapter 3: Electric Priming Essentials

• Use a galvanometer to measure electrical resistance and ensure circuit continuity.
• Electric blasting caps need a dry cell battery for operation.
• Ensure compatibility of caps from the same manufacturer to avoid misfires.

Chapter 4: Preparing and Testing the Cap

• Remove the cap from its container and uncoil the lead wires.
• Secure the cap to prevent impact damage.
• Remove the shunt to enable testing.
• Use the galvanometer to check for a complete circuit:
  • A deflection indicates a good cap.
  • If there's no deflection, troubleshoot the circuit.

Chapter 5: Setting Up the Firing System

• Twist the ends of the cap wires together to short the circuit.
• Test the firing wire by closing one end and checking continuity with the galvanometer.
• The blasting machine is the final component needed to supply current for detonation.

Chapter 6: Priming Methods for Different Charges

• For threaded cap wells: Use a priming adapter to secure the cap.
• For non-threaded cap wells: Secure the cap with two half hitches around the charge.
• For C4 and dynamite: Punch cap wells manually and ensure sufficient explosive material surrounds the cap.
• For special charges: Such as Bangalore torpedoes, use the appropriate priming techniques.

Chapter 7: Connecting Charges

• Use a ring main system made of detonating cord for better safety and control.
• In a dual firing system, each ring main should be independent to minimize misfire risks.
• For circular patterns, use a Western Union pigtail splice for connections.

Chapter 8: Safety and Final Checks

• The NCO in charge must oversee the entire operation and ensure all connections are secure.
• Before firing, inspect the area and signal “fire in the hole” three times.
• If charges do not detonate, check the circuit with the galvanometer and troubleshoot individual components.

Chapter 9: Troubleshooting Misfires

• If a charge does not fire, disconnect and recheck the circuit.
• With underground charges, wait for 30 minutes before investigating.
• Use a primed charge close to any faulty cap to safely initiate detonation.

Conclusion

Performing demolition work requires meticulous preparation and adherence to safety protocols. Mastery of electric priming techniques, along with thorough testing and troubleshooting methods, is essential for successful operations. Always prioritize safety, and ensure all team members are aware of their roles and responsibilities. For further learning, consider practical training exercises or simulations to enhance your skills in demolition techniques.