Demolition Flashcards
What are the types of block demolition charges the Army uses?
TNT M112 block (C4) M118 block M118 sheet Ammonium Nitrate M1 Dynamite H6 Cratering Charges
For charges over 500 lbs what’s the safe distance formula?
Distance in Feet = 300 x cube root (lbs of explosives)
Distance in Meters = 100 x cube root (lbs of explosives)
What’s the minimum safe distance for a 500 lb charge when you’re in a missile-proof shelter?
328 feet
Should you ever divide responsibility when preparing, placing, priming, or firing charges?
No.
When should you be 1,000 meters away from a detonation site?
When detonating explosives on steeling, Bangalore torpedoes, and mines. (100 meters if you’re in a missile proof shelter)
What should you never mix during transport?
Explosives and Detonators.
What does 1 meter equal in feet?
3.28 ft
What does 1 kg equal in pounds?
2.20 lbs
What does 1 foot equal in meters?
0.3048 meters
What does 1 lb equal in kg?
4.536 kg
What are the steps to solving a demo problem?
- Identify and measure critical dimensions
- Calculate for TNT/Rule of Thumb
- Divide by RE factor
- Divide by package weight/volume round up to next whole package
- Calculate number of charges
- Calculate total amount of explosives
How close can you be to power lines with electric detonators?
155 meters
What is the formula to cut timber with a tamped, internal charge?
P = D^2/250
What is the formula for cutting timber Abatis?
P = D^2/50
What is the formula for external charges when cutting timber?
P = D^2/40
Where do you place the charges when cutting timber to produce a fall in a desired direction?
On the side you want the fall to happen on.
What are the rules of thumb when blowing a dead stump?
- For dead stumps, use 1 lb of explosive per foot of diameter. Place charge 1 foot deep for every foot of diameter.
- For green stumps, use 2 lbs of explosive per foot of diameter. Place charge 1 foot deep for every foot of diameter.
- For standing timber, increase charge size by 50%
What’s the formula for cutting steel?
P = 3/8 * cross section in in^2
What’s the formula for cutting high-carbon steel, alloy steel, or slender steel members?
P = D^2
What are the rules of thumb for cutting mild circular sections such as chains, rods, and cables?
- Less than 1 inch in diameter, use 1 lb of TNT
- More than 1 inch but less than 2 inches use 2 lbs of TNT
- Over 2 inches use P = 3/8 x Area
What are the rules of thumb for Special Demolition Techniques?
- For railroads 5 inches or higher, use 1 lb of any explosive.
- For railroads less than 5 inches, use 1/2 lb of any explosive.
- For a ditch that measures a cubic yard of earth, use 1 lb of explosive.
What’s the formula for the number of holes in a cratering charge?
N = L - 16/5 + 1
What are the rules for a Hasty Crater?
- Dig all holes (minimum of 3) at least 5 feet deep.
- Use 10 lb explosives per 1-foot of depth.
- The crater should be 1 1/2 times the depth of the boreholes. Its width should be about 5 times the depth of the boreholes.
Notes: Dual prime all cratering charges with 1 lb of explosives. Prime cratering charges with detonating cord. Do not use blasting caps below ground.
What are the rules for a Deliberate Crater?
Alternate 5’ and 7’ holes spaced on 5’ centers
Never place two 5’ holes next to each other. Place 7’ holes at the ends.
Use 40 lb charges in 5’ holes and 80 lb charges in 7’ holes.
The crater should be 8’ deep and 25’ wide
What are the rules for relieved-face cratering?
Layout friendly row first.
Lay out enemy row with holes centered between friendly holes.
Detonate enemy row first.
Detonate friendly row with a 1/2 to 1 1/2 second delay after enemy row.
Friendly holes = L - 10/7 + 1
Enemy holes = Friendly Holes - 1
What is explosive material?
A substance that is chemically or otherwise energetically unstable or produces a sudden expansion/reaction of the material, usually accompanied by the production of heat and large violent changes in pressure. This happens during the transfer from a solid to a gaseous state, releasing pressure in all direction. Typically a flash and/or loud noise upon initiation follows. This reaction is referred to as an explosion.
What is a low velocity charge?
Explosives that change from a solid to a gaseous state over a sustained period up to 400 m/sec. This type of explosive is ideal for pushing
What is a high velocity charge?
Explosives that change to a gaseous state almost instantaneously @ 1000 m/sec. This type of explosive produces a shattering effect
What is an RE factor and what does it stand for?
Relative Effectiveness: the shattering effect of explosive in relation to that of TNT
What is C4’s velocity and what’s it’s RE?
8,040 m/s and 1.34
What are the characteristics you look for in an explosive?
Economical
Insensitivity
Shattering Effect
Stability
High Density
Low Toxicity
Underwater Use
Size and Shape
What are the types of construction demo uses?
Abatis - to create an obstacle to prevent personnel and vehicle.
Bridges - by blowing out abutment and leveling surface.
Craters - to stop tanks and vehicle.
Protective Shelters – Reduces digging time and effort – Not recommended for excavation less then 2 feet
Quarrying Operations - there is a special MOS for quarrying operation.
Tank Ditches - using cratering charge to stop tanks.
Trenches and Ditches - blown out with explosive for troops defensive position
Weapon emplacement - clear fields of fire.
Land Clearing – removing trees/stumps for Airfield/Airlift Operations
What are the types of destruction demo uses?
Airfields – creating craters on the surface to prevent planes from landing/taking off
Bridges - either partial or total destruction using all types of explosive
Buildings – to prevent use by the enemy
Equipment
Log Cribs - also prevent troops from moving in an area of operation.
Steel and Log Post obstacle - prevent movement of troops through an area of operation.
Wire and Concrete Obstacles - prevent movement of troop through an area of operation
What is Det Cord?
Prime or detonate other explosives remotely. Det velocity of 20,000 to 24,000. Charge weight 6.4 lbs per 1000 ft. Total weight is 18 lbs per 1000’. Filed with PETN. Moisture can penetrate up to 6’’.
6’’ of det cord equals a blasting cap.
Avoid cross overs or stepping on it. Hard to tie or work with in cold weather.
What is Ammonium Nitrate?
Least Sensitive of military explosives
Requires a booster for successful detonation
Not suitable for breaching or cutting charges due too low detonating velocity
Needs to be sealed “airtight” because it absorbs humidity
Not reliable for underwater demolitions
Commercial quarrying operations
What is TNT?
TNT is used to rate all other military explosives
Has a high detonating velocity
Used for all types of demolition missions except special steel cutting charges
Cannot be molded but water resistant
Not recommended to use in closed spaces due to the toxicity
How many 1 lb charges in a box of TNT and what is a 1 lb charge’s dimensions?
48 and 1.75’’ x 1.75’’ x 7’’
What is C4 (M112)?
RE = 1.34
C4 is a composite explosive containing 91% (RDX) and 9% non-explosive plasticizers
C4 looses its plasticity in colder temps
Primarily use for cutting and breaching
Ideal for cutting steel or irregularly shaped targets
Adhesive backing allows the charge to be put on any relatively flat, clean and dry surface, above freezing
Molding the charge can decrease the cutting effect
Primary block demolition charge in use today
Do not eat or chew!!!! Very poisonous
How much does a block of C4 weigh, how many are in a box and what is the dimension?
30 per box, 1.25 lbs, 1’’ x 2’’ x 10’’ (20 cubic inches)
What is Military Dynamite?
RE = 0.92
Is a composite that contains 75%(RDX),15% TNT, and 10% desensitizers and plasticizers.
Military Dynamite is not as powerful as commercial dynamite.
The equivalent strength of military dynamite is 60% of commercial dynamite
Because military dynamite contains no nitroglycerin, it is more stable, safer to store, transport and handle then commercial version
Suitable for underwater operations, no more than 24 HRS
Not suitable for cutting or breaching
What are the dimensions of TNT?
0.5 lbs, 1.25’’ D, 8’’ long. Primarily used for quarrying, ditching, and stump removal.
What is a M1A2 bangalore torpedo?
Main charge = 10.5 lbs + Two End Boosters = 0.5 lbs = 11.5 lbs total.
Each tube is 5’ long.
Best use is clearing paths through wire obstacles and heavy undergrowth. It will clear a 3 - 4 yard wide path through wire obstacles
What is a M1A3 bangalore torpedo?
Main charge = 5 lbs + Two End Boosters = 0.5 lbs = 5 lbs total.
Each tube is 2.5’ long.
Best use is clearing paths through wire obstacles and heavy undergrowth. It will clear a 3 - 4 yard wide path through wire obstacles
What is the Monroe or Neumann Effect?
The Munroe effect or Neumann effect refers to the partial focusing of blast energy caused by a hollow or void cut into a piece of explosive, a property which is exploited by a shaped charge.
What does MDI stand for?
Modern Demolition Initiator
What are the types of MDIs?
M11 (High Strength Blasting Cap) M12 (Low Strength Blasting Cap) M13 (Low Strength Blasting Cap) M15 M16 M19 (replace 12 and 13, branch lines) M21 M23 (replace 12 and 13, branch lines) M151 M152
What is an MDI?
MDI is the project name given to a new family of non-electric blasting caps, non-electric boosters, and associated items
MDIs supplement and partially replace the M7 non-electric blasting cap, the M6 electric blasting cap, and the M700 time fuse
The snap-together MDI components simplify initiation systems and some types of explosive priming. In some cases, emplacement times can be decreased by up to 50 percent
MDIs also improve reliability and safety. One reason for this reliability is the fact that all of the components are sealed and, unlike standard non-electric priming components, cannot be easily degraded by moisture. .5 failure rate
What is the M11?
Used as a branch line to a primary charge, shock tube or Det Cord
30 FT Length of shock tube with factory attached high strength blasting cap
Moveable, plastic connector(J Hook) to allow connection to Det Cord
Yellow(2 meter) and Red (1 meter) flags spaced away from the blasting cap
What is the M14 and M18?
Blasting cap delay
Detonate explosives
Ignite shock tube
Provide a standoff
5 minute delay (M14)
Length may vary
(M18 has 20 minute delay)
What is the M151?
Non-electric booster
Used as a branch line to a primed charge (above or below ground)
Is factory crimped to a 10ft. length of lower strength detonating cord (19500fps vs. 25000fps)
Can be buried and used for branch lines.
What is M152?
Same physical & operational characteristics as M151 only with 30ft.
Never ignite M151/M152 directly from M81 igniter
Do not secure M151/M152 ,shock tube or Det Cord in the same holder
What is the M12 and M13?
Transmission line only
M12 has low strength cap. It does not have enough output to initiate military explosives reliably except for one strand of Det Cord
M12 is 500’ and M13 is 1000’
What is the M81?
Fuse ignitor
What’s an M21 and M23?
Replaces the existing M12 & M13
Now has a HIGH strength blasting cap (same as the M11)
Factory crimped to 500’ or 1000’ of mini tube which is shock tube reduced (wt. & size) by approx 40%
Has an in line initiator (similar to an M81)
