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FM Chapter 1. Military Explosives. Section I. Demolition Materials. . according to instructions and directives of theater commanders. Captured. FM DEPARTMENT OF THE ARMY FIELD MANUAL. EXPLOSIVES. AND. DEMOLITIONS .. soldiers and then only according to instructions and directives . (FM ). Department of the Army. Washington, DC, 11 July EXPLOSIVES AND DEMOLITIONS. Contents. Page. PREFACE.

Search the history of over billion web pages on the Internet. Books by Language. Full text of " U. Take the time to read this, it is like an undergraduate degree in explosive demolitions. This manual describes the characteristics and proper use of every type of explosive in military use today.

The two types of blasting caps are electric and nonelectric. They are designed for insertion into cap wells and are. Blasting caps are rated in power, according to the size of their main charge. Commercial blasting caps are normally Number 6 or 8 and are for detonating the more sensitive explosives, such as commercial dynamite and tetryl. Special military blasting caps M6 electric and M7 nonelectric ensure positive detonation of the generally less sensitive military explosives.

Their main charge is about double that of commercial Number 8 blasting caps. Never carry blasting caps loose or in uniform pockets where they are subject to shock.

Separate blasting caps properly. Never store blasting caps with other explosives. Do not carry blasting caps and other explosives in the same truck except in an emergency.

See Chapter 6. Do not tamper with blasting caps. Protect them from shock and extreme heat. Use electric blasting caps for command detonation or when a source of electricity, such as a blasting machine or a battery, is available. Both military and commercial caps may be used. Military caps Figure operate instantaneously. Commercial caps may operate instantaneously or have a delay feature. The delay time of commercial caps for military applications ranges from 1 to 1. Electric caps have lead wires of various lengths.

The most common lead length is 12 feet. Electric caps require 1. The standard-issue cap is the M6 special electric blasting cap. TM gives additional information on blasting caps. Limited quantities will be available for special purposes once MDI is fully fielded. Plug assembly Aluminum alloy cup Short-circuiting tab must be removed before connecting caps in firing circuit Lead wires.

M6 special on Lead wires cardboard spool Aluminum alloy cup Plug assembly. Initiate these caps with time blasting fuse, a firing device, or detonating cord Figure Avoid using nonelectric blasting caps to prime underwater charges because the caps are hard to waterproof. If necessary, waterproof nonelectric blasting caps with a sealing compound. The M7 nonelectric blasting cap is the standard issue.

The open end of the M7 nonelectric blasting cap is flared to allow easy insertion of detonating cord time fuse. Ignition charge 2.

An M1A4 is a plastic, hexagonal-shaped device, threaded to fit threaded cap wells. The shoulder inside the threaded end will allow a time blasting fuse and detonating cord to pass, but the shoulder is too small to pass a military blasting cap. To accommodate electric blasting caps, the adapter has a lengthwise slot that permits blasting cap lead wires to be installed in the adapter quickly and easily Figure An M8 is a metal clip designed to attach a blasting cap to a sheet explosive Figure These clips are supplied with the M and M charges.

The M8 is also available as a separate-issue item in quantities of 4, An M1 clip is a device for holding two strands of detonating cord together, either parallel or at right angles Figure , diagram 1. Priming adapter Priming adapter Electric blasting cap.

Cap wire Cap pulled into adapter. Knots, if left for extended periods, may loosen and fail to function properly. Connect a detonating-cord branch line by passing it through the trough of the M1 clip and through the hole in the tongue of the clip. Figure , diagram 2.

Splice the ends of detonating cords by first overlapping them approximately 12 inches. Then secure each loose end to the other cord by using a clip. Finally, bend the tongues of the clips firmly over both strands.

Make the connection stronger by bending the trough end of the clip back over the tongue Figure , diagram 3. Clip before bending Branch-line connection Diagram 1 Diagram 2.

Splicing two cords Diagram 3. M1 adhesive paste is a sticky, putty-like substance that is used to attach charges to flat, overhead or vertical surfaces. Adhesive paste is useful for holding charges while tying them in place or, under some conditions, for holding without ties. This paste does not adhere satisfactorily to dirty, dusty, wet, or oily surfaces. M1 adhesive paste becomes useless when softened by water. This tape is replacing M1 adhesive paste.

The tape has better holding properties and is more easily and quickly applied. This tape is coated on both sides with pressure-sensitive adhesive and requires no solvent or heat to apply. It is available in 2-inch-wide rolls, 72 yards long. Use this tape to effectively hold charges to dry, clean wood, steel, or concrete. This tape does not adhere to dirty, wet, oily, or frozen surfaces. This sealant is for waterproofing connections between time blasting fuses or detonating cords and nonelectric blasting caps.

The sealing compound will not make a permanent waterproof seal. Since this sealant is not permanent, fire underwater demolitions as soon as possible after placing them. Use an M2 cap crimper Figure for squeezing the shell of a nonelectric blasting cap around a time blasting fuse, standard coupling base, or detonating cord. Crimp the shell securely enough to keep the fuse, base, or.

A stop on the handle helps to limit the amount of crimp applied. The M2 crimper forms a water-resistant groove completely around the blasting cap. Apply a sealing compound to the crimped end of the blasting cap to waterproof it. The cutting jaw, located on the leg, is shaped and sharpened for cutting fuses and detonating cords. One leg of the handle is pointed for punching cap wells in explosive materials. The other leg has a screwdriver end. Cap crimpers are made of a soft, nonsparking metal that conducts electricity.

Do not use them as pliers because such use damages the crimping surface. Ensure that the crimp hole is round not elongated and the cutting jaws are not jagged.

Keep the cutting jaws clean, and use them only for cutting fuses and detonating cords. Screw-driver end Cutting jaw. The M51 is a self-contained unit with a magneto-type impulse generator, an indicator lamp, a handle to activate the generator, and two binding posts for attaching firing leads. Check the continuity of firing wire, blasting caps, and firing circuits by connecting the leads to the test-set binding posts and then depressing the handle sharply.

If there is a continuous intact circuit, even one created by a short circuit, the indicator lamp will flash. When the circuit is open, the indicator lamp will not flash. Handle the test set carefully, and keep it dry to ensure optimum use.

Before using, ensure that the test set is operating properly by using the following procedures: The indicator lamp should flash. This time the indicator lamp should not flash. Blasting machines provide the electric impulse needed to initiate electric blasting-cap operations. When operated, the M32, M34, and CDJ models use an alternator and a capacitor to energize the circuit.

This small, lightweight blasting machine Figure produces adequate current to initiate 10 electrical caps connected in a series using feet of wire diameter WD -1 cable. To operate the machine, use the procedure for the M cap blasting machine. This small, lightweight machine produces adequate current to initiate 50 electrical caps connected in a series.

It looks like the M32 blasting machine Figure except for a black band around the base and a reinforced-steel actuating handle. Release the blasting- machine handle by rotating the retaining ring downward while pushing in on the handle. The handle should automatically spring outward from the body of the machine.

The lamp is located between the wire terminal posts and cannot be seen until it flashes, since it is covered by green plastic. Be sure to hold the machine correctly, as the handles are easily broken. Normally, no more than three or four strokes are required. Conduct an operational test on the CDJ as follows: Continue holding both switches down for 3 seconds.

Release both switches after observing the above and then secure the blasting machine. General Operating Procedures Conduct general operating procedures on the CD as follows: Contact with electrical conductors could cause serious injury or death. Continue holding both switches down until the firing operation is complete. If the blasting machine should fail to fire, release both switch- es, disconnect and shunt the lead lines, and notify personnel of blast delay. Wire for firing electric charges is available in and foot coils.

This wire is wound on an RL39A reel unit. The single-conductor, AWG Number 20 annunciator wire is available in foot coils and is used to make connections between blasting caps and firing wire.

REEL The RL39A reel, with spool, accommodates feet of wire. The reel has a handle assembly, a crank, an axle, and two carrying straps Figure The fixed end of the wire extends from the spool through a hole in the side of the drum and fastens to two brass thumb-out terminals. The carrying handles are two U-shaped steel rods. A loop at each end encircles a bearing assembly to accommodate the axle. The crank is riveted to one end of the axle, and a cotter pin holds the axle in place on the opposite end.

Carrying straps Reel. This device is used for igniting timed blasting fuse in all weather conditions, even underwater, if properly waterproofed. Insert the fuse through a rubber sealing grommet and into a split collet. This procedure secures the fuse when the end cap on the igniter is tightened Figure With the safety pin removed, pulling the pull ring releases the striker assembly, allowing the firing pin to initiate the primer, igniting the fuse.

Chapter 2 gives detailed operating instructions for the M60 igniter. This set electric and nonelectric explosive initiating demolition equipment set is an assembly of tools necessary for performing demolition operations Table Demolition equipment set Quantity Nomenclature Quantity Nomenclature 4 Crimper, blasting cap, M2 4 Reel, cable Knife, pocket, with can opener Machine, cable-reeling, manual 2 1 and punch Knife, pocket, with screwdriver Tape, measuring, steel, milli- 2 2 and wire scraper meters and inches Shears, metal-cutting, manual, Set, blasting-cap test, M51 1 1 8-inch Tape, measuring, plastic-coated, 1 foot NOTE: The items listed in this set are available separately.

The different types of initiating sets and how to prepare them are explained in this chapter. Also discussed are the different methods for priming each type of explosive and how to set up demolition firing systems. A nonelectric system uses a nonelectric blasting cap as the initiator. The initiation set consists of a fuse igniter produces flame that lights the time fuse , a time blasting fuse transmits the flame that fires the blasting cap , and a nonelectric blasting cap provides shock adequate to detonate the explosive Figure See Chapter 7 for MDI components and the preparation sequence.

When combined with detonating cord, a single initiation set can fire multiple charges. Fuse-holder cap Time blasting Nonelectric Pull ring fuse blasting cap. Preparing demolitions for nonelectric initiation follows a specified process. This process includes the steps listed below. Step 1. Check the time fuse. Test every coil of fuse, or remnant of a coil, using the burning-rate test before use. One test per day per coil is sufficient. Never use the first and last 6 inches of a coil because moisture may have penetrated the coil to this length.

Using an M2 crimper, cut and discard a 6-inch length from the working end of the fuse Figure Cut a 3-foot length of the fuse to check the burning rate. Ignite the fuse and note the time it takes for the fuse to burn. Compute the burning rate per foot by dividing the burn time in seconds by the length in feet. If the test burn does not fall within 5 seconds of a second-per-foot burn rate, perform another test to verify your results.

Once the burn rate is calculated, it is recommended that the coil be placed in the foil packet and marked with its corresponding burn rate. Step 2. Prepare the time fuse. Cut the fuse long enough to allow the person detonating the charge to reach safety walking at a normal pace before the explosion. Walk and time this distance before cutting the fuse to length. The formula for determining the length of time fuse required is—.

Do not cut the fuse too far in advance, since the fuse may absorb moisture into the open ends. Do not allow the time. Step 3. Attach the fuse igniter. To attach an M81 weatherproof fuse igniter, unscrew the fuse holder cap two or three turns, but do not remove the cap.

Press the shipping plug into the igniter to release the split collet Figure , page Rotate and remove the plug and plastic shock tube holder from the igniter.

Insert the free end of the time fuse as far as possible into the space left by the removed shipping plug. Sufficiently tighten the holder cap to hold the fuse and weatherproof the joint. Step 4. Install the priming adapter. If you use a priming adapter to hold a nonelectric blasting cap, place the time fuse through the adapter before installing crimping the blasting cap onto the fuse. Ensure that the adapter threads are pointing to the end of the time fuse that will receive the blasting cap.

Step 5. Hold the cap between the thumb and ring finger of one hand, with the forefinger of the same hand on the closed end of the blasting cap.

Inspect the blasting cap by looking into the open end. You should see a yellow-colored ignition charge. If dirt or any foreign matter is present, do the following: Use the following procedures to attach a nonelectric blasting cap to the time fuse or the detonating cord: Never force a time fuse into a blasting cap, for example, by twisting.

If the fuse end is flat or too large to enter the blasting cap freely, roll the fuse between the thumb and fingers until it will freely enter the cap. A rough, jagged-cut fuse inserted in a blasting cap can cause a misfire. If the cutting jaws of the M2 crimper are unserviceable, use a sharp, nonsparking knife to cut the fuse.

When using a knife to cut fuse squarely, cut the fuse against a solid, nonsparking surface such as wood. The thumb and ring finger that hold the fuse will be below the crimpers. Rest the second finger of the hand holding the fuse on top of the crimpers to prevent the crimpers from sliding up the cap Figure Protect the joint between the cap and the time blasting fuse with a coat of sealing compound or a similar substance if the blasting cap is to remain in place several days before firing.

This sealing compound does not make a waterproof seal; therefore, fire submerged charges immediately. Inspect the crimp after you have finished. Attach the M60 fuse igniter to the time fuse before crimping a blasting cap to the opposite end. Do not remove the safety pin until you are ready to detonate the charge. If the cap is to remain in place several days before firing, pro- tect the joint between the cap and the timed blasting fuse with a coat of sealing compound or similar substance.

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See paragraphs through , pages through , for procedures on handling nonelectric misfires. To fire the assembly, hold the M60 igniter in one hand, and remove the safety pin with the other. Grasp the pull ring and give it a quick, hard pull. In the event of a misfire, reset the M60 by pushing the plunger all the way in, rotate it left or right o, and attempt to fire as before. This will prevent the fuse igniter from working after resetting. If a fuse igniter is not available, light the time blasting fuse with a match.

Split the fuse at the end Figure , and place the head of an unlit match in the powder train. Light the inserted match head with a flaming match, or rub the abrasive on the match box against it. It may be necessary to use two match heads during windy conditions.

See Appendix F for the power requirements for series firing circuits. Use the following process to make an electric initiation set: Testing and maintaining control of the blasting machine.

The supervisor is responsible for this.

Testing the M51 test set. Testing the firing wire on the reel shunted and unshunted. Squeeze the test-set handle. The indicator lamp should NOT flash. If it does, the lamp's flash indicates a short circuit in the firing wire Figure Uninsulated portions of wires are separated at both ends.

Lamp flashes Unshunted. Defective Satisfactory Uninsulated portions of wires are twisted together at one end. Lamp does not flash Shunted Lamp flashes. If it does not, the lamp's failure to light indicates a break in the firing wire Figure Use at least three degree twists to shunt the wires. Laying out the firing wire completely off the reel. Ensure that this firing point is located a safe distance away from the charges paragraphs and , pages through Always bury firing wire or lay it flat on the ground.

Avoid creating any loops in the wire lay it in as straight a line as possible. Cut the wire to length. Do not connect it to a blasting machine through the unused portion of wire on the reel. Retesting the firing wire shunted and unshunted. The process of unreeling the wire may have separated broken wires not found when the wire was tested on the reel. Do this to ensure that no one tampers with the wires or fires the charges prematurely.

Hand signals are necessary because of the distance involved between the charges and the firing position. The soldier testing the wire also can give these signals directly to the soldier at the opposite end of the wire or, if they cannot see each other, through intermediate positions or over the radio. The tester indicates to his assistant that he wants the far end of the firing wire unshunted by extending both arms straight out at shoulder height.

After unshunting the firing wire, the assistant at the far end of the wire repeats the signal, indicating to the tester that his end is unshunted. When the tester wants the far end of the firing wire shunted, he signals to his assistant by clasping his hands together and extending his arms over his head, elbows bent, forming a diamond shape. After shunting the firing wire, the assistant repeats the signal, indicating to the tester that his wire is shunted.

Step 6. Testing the electric blasting caps. Place the cap in the palm of your hand, lead wires passing between your index and middle fingers. Doing this prevents tension on the wires in the cap and prevents the cap from being dropped. Completely unreel the cap wires from the cardboard spool. Avoid allowing the wires to slip off the ends of the cardboard spool, since this will cause excessive twists and kinks in the wires and prevent the wires from separating properly.

Keep your back to the blasting cap when testing it. Hold or attach the second lead wire to the other binding post, and squeeze the test-set handle. The blasting cap is good if the indicator lamp flashes. If the lamp does not flash, the cap is defective; do not use it. Step 7. Connecting the series circuit if used. For a series circuit, you may use one of the series circuits illustrated in Figure Use the following procedure:.

Protect all joints in the circuit with electrical insulation tape. Do not use the cardboard spool that comes with the blasting cap to insulate these connections.

After the series is completed, connect the two free blasting-cap wires to the M51 test set. The indicator lamp should flash to indicate a good circuit.

If the lamp does not flash, check the connections and blasting caps again. Step 8. Connecting the firing wire to the cap wire. Step 4 Knot keeps tension off splice Step 2 Step 5. Never use the cardboard spool that comes with the blasting cap to insulate this connection.

The firing wire is likely to break when bent to fit into the spool. Step 9. Testing the entire firing circuit. Before priming the charges with electric caps or connecting the blasting caps to the firing circuit, test the circuit from the firing point. Use the following procedure: Squeeze the test handle.

The indicator lamp should flash, indicating a proper circuit. WARNING Do not prime charges with electric blasting caps or connect electric blasting caps to the detonating cord until all other steps of the preparation sequence have been completed.

Step Priming the charges. Prime the charges and return to the firing point. This is the last step before actually returning to the firing point and firing the circuit. An electric system uses an electric blasting cap as the explosion initiator. The initiation set consists of an electric blasting cap, the firing wire, and a blasting machine Figure An electric impulse usually provided by a blasting machine travels through the firing wire and blasting-cap leads, detonating the blasting cap which initiates the explosion.

Radio waves can also detonate electric blasting caps. Therefore, observe the minimum safe distances listed in the tables in Chapter 6, at all times.

A single initiation set ca n be used to initiate the detonating cord or multiple charges. Electric blasting cap. At this point, the initiation set is complete. Do not connect the blasting machine until all personnel are accounted for and you have clearance to fire the demolition. Chapter 6 covers procedures for electric misfires. Strip the insulating material from the end of insulated wires before splicing. Also remove any coating on the wire, such as enamel, by carefully scraping the wire with the back of a knife blade or other su i ta b l e to o l.

T w is t multiple-strand wires lightly after scraping. Method Use the Western Union pigtail splice Figure , page to splice two wires. Splice two pairs of wires in the same way as the two-wire splice Figure Diagram 1 Firing wire. Precautions A short circuit may occur at a splice if you do not use caution. For example, when you splice pairs of wires, stagger the splices and place a tie between them Figure , diagram 1. Another method of preventing a short circuit in a splice is using the alternate method Figure , diagram 2.

In the alternate method, separate the splices rather than stagger them. Insulate the splices from the ground or other conductors by wrapping them with friction tape or electric insulating tape.

Always insulate splices. Use a common series circuit to connect two or more electric blasting caps to a single firing wire Figure , page Prepare the circuit by connecting one blasting cap to another until only two lead wires are free. Shunt the two lead wires until you are ready to proceed with the next step.

Leapfrog The leapfrog method of connecting caps in a series is useful for firing any long line of charges Figure , page This method is performed by starting at one end of a row of charges and priming alternate charges to the opposite end and then priming the remaining charges on the return leg of the series.

This method eliminates the necessity for a long return lead from the far end of the line of charges. See Appendix F for additional information on series circuits. This type of circuit is rarely needed, since detonating cord, when combined with a single blasting cap, will fire multiple charges.

The three methods of priming charges are nonelectric, electric, and detonating cord. Nonelectric and electric priming involves directly inserting blasting caps into the charges. Use the direct-insertion method only when employing shaped charges. Detonating-cord priming is the preferred method for priming all other charges since it involves fewer blasting caps, makes priming and misfire investigation safer, and allows charges to be primed at state of readiness—state 1 safe when in place on a reserved demolition target or mission.

You can crimp nonelectric blasting caps to detonating cord as well as time fuse. This capability permits simultaneous firing of mul- tiple charges primed with a blasting cap. TNT blocks have threaded cap wells. Use priming adapters, if available, to secure nonelectric blasting caps and timed blasting fuses to TNT blocks with threaded cap wells Figure When priming adapters are not available, prime TNT blocks with threaded cap wells as follows: Adhesive tape can also effectively secure blasting caps in charges.

Refer to Figure Priming adapter Nonelectric blasting cap. Cap well Time fuse Demolition block Blasting cap 6". Do not tie string so tightly that the powder train is broken in the fuse. Substitute electrical or friction tape for string, if necessary. Use the following procedure for priming TNT block, using the priming adapter: Ensure that the blasting cap protrudes from the threaded end of the adapter. Without Priming Adapter If a priming adapter is not available, use the following procedure: Tie the lead wires around the block, using two half hitches or a girth hitch Figure , page Allow some slack in the wires between the blasting cap and the tie to prevent any tension on the blasting-cap lead wires.

Use the following methods to prime TNT blocks with detonating cord: Lay one end 1-foot length of detonating cord at an angle across the explosive. Then, wrap the running end around the block three turns, laying the wraps over the standing end. On the fourth wrap, slip the running end under all wraps, parallel to the standing end and draw the wraps tight. This forms a clove hitch with two extra turns. Place a loop of detonating cord on the explosive, leaving sufficient length on the end to make four turns around the block and loop with the remaining end of the detonating cord.

When starting the first wrap, ensure that you immediately cross over the standing end of the loop, working your way to the closed end of the loop. Pass the free end of the detonating cord through the loop, and pull it tight. This forms a knot around the outside of the block. C4 blocks do not have a cap well; therefore, you will have to make one. If the blasting cap does not fit the hole or cut, do not force the cap; make the hole larger.

To prime plastic explosives with detonating cord, use the following procedure: Form either a Uli knot, a double overhand knot, or a triple roll knot as shown in Figure , page Ensure the space is large enough to insert the knot you formed Figure , page Uli knot 8 wraps minimum Minimum 6" tail. It is not recommended that plastic explosives be primed by wrapping them with detonating cord, since wraps will not properly detonate the explosive charge.

Use one of the following methods to prime M and M demolition charges: Attach an M8 blasting-cap holder to the end or side of the sheet explosive. Insert an electric or a nonelectric blasting cap into the holder until the end of the cap presses against the sheet explosive. The M8 blasting-cap holder has three slanted, protruding teeth which prevent the clip from withdrawing from the explosive.

Two dimpled spring arms firmly hold the blasting cap in the M8 holder. Electric or nonelectric blasting cap Method 1 Method 3 3". Insert the blasting cap to the limit of the notch. Secure the blasting cap with a strip of sheet explosive. Sheet explosives also can be primed with detonating cord using a Uli knot, double overhand knot, or triple roll knot.

Insert the knot between two. Prime dynamite at either end or side using one of the following methods: There are three methods for priming dynamite nonelectrically: Slightly slant the cap well so the blasting cap, when inserted, will be nearly parallel to the side of the cartridge and the explosive end of the cap will be at a point nearest the middle of the cartridge step 1.

Then, wrap the string tightly around the cartridge, making two or three turns before tying it step 3. Cover the string with a weatherproof sealing compound step 4. You also can use detonating cord to prime dynamite. Using the M2 crimpers, start about 1 inch from either end of the dynamite charge, and punch four equally spaced holes through the dynamite cartridge Figure Make sure to rotate the cartridge o after punching each hole to keep the holes parallel.

Lace detonating cord through the holes in the same direction that you punched the holes. Take care not to pull the loops of the detonating cord too tightly or the dynamite will break. Secure the detonating cord tail by passing it between the detonating cord lace and the dynamite charge. The cratering charge is primarily an underground charge; therefore, prime it only with C4 primed with detonating cord.

Use dual priming to protect against misfires. Firmly hold them in place with miles-per- hour tape. Instructions and markings on the canister indicate the exact placement of the C4 Figure , diagram 3.

This requires one primed C4 block on each of the cratering charges, parallel to the charges and flush with the top. When placed in the borehole, the C4 blocks are placed on opposite sides of the pound charges Figure , diagram 4. To aid in clearing possible misfires, you should place tape on the detonating cord from the cratering charge, one foot up.

C4 or TNT block connected with detonation cord Rotate and have placed on detonation cord opposite side of go through the detonation cord detonation cord Single or tunnel. Two pound crater charges in one borehole, dual-primed, C4 on opposite sides One pound cratering charge, dual-primed, C4 on opposite sides. The com position H6 cra te ring charge replaced the 4 0- pound ammonium-nitrate cratering charge. If an ammonium-nitrate cratering charge is drawn from an ammunition supply point ASP , use the following procedure to prime it: Tie an overhand knot with a 6-inch tail at the lower end of the length of the detonating cord.

Use a minimum of 1 pound of explosive when dual priming a single cratering charge. Prime the explosive with detonating cord and tape the charge. The borehole is dual-primed, and extra explosives are not required as shown in Figure , diagram 2. Therefore, inspect the metal container for damage or rust. Do not use damaged or rusty charges. The M2A4 and M3A1 are primed only with electric or nonelectric blasting caps.

These charges have a threaded cap well at the top of the cone. Prime them with a blasting cap as shown in Figure Use a piece of string, cloth, or ta pe to hold the cap if a priming ad apter is not availab le. Simultaneously detonate multiple shaped charges to create a line of boreholes for cratering charges by connecting each charge into a detonating-cord ring or line main.

The procedure for priming shaped charges are listed below. Prime them only with a blasting cap in the threaded cap well. Prime nonelectric shaped charges as follows: Prime electric shaped charges as follows: The basic procedure is CTP.

Priming adapter M3 shaped charge. Time fuse or Nonelectric detonating cord blasting cap. Priming adapter Electric blasting Without priming adapter cap.

M2 crimpers Friction tape or string. Friction tape or string Time fuse or Nonelectric detonating cord blasting cap. Insert a blasting cap of a nonelectric initiation set directly into the cap well of a torpedo section Figure , diagram 1, page If a priming adapter is not available, use tape or string to hold the blasting cap in place.

When priming the bangalore with a nonelectric cap, use the crimp, tie, prime CTP method. Insert the blasting cap of an electric initiation set into the cap well of a torpedo section.

If a priming adapter is not available, hold the cap in place by taping or tying with two half hitches the lead wires to the end of the torpedo. Allow some slack in the wires between the blasting cap and the tie to prevent tension on the blasting cap leads, and use a tension knot to join the firing wire to the cap wire.

Diagram 1 M2 crimpers Bangalore torpedo. Firing wire Diagram 2 Cap wire Bangalore torpedo Electric blasting cap. Prime the torpedo by wrapping the detonating cord eight times around the end of the section, just below the bevel Figure After pulling the knot tight, insert the short end of the detonating cord into the cap well, and secure it with tape, if needed. Never use the short end tail of the detonating cord to initiate the torpedo.

Initiation must come from the running end of the detonating cord. Tail Count from back side. When dual priming the torpedo with two branch lines, wrap detonating cord four times around the end of the section with one branch line, and repeat the procedure for the remaining branch line. Make sure that the wraps are. Another method that you can use to dual prime the bangalore torpedo, but only as a last resort, is to tie eight wraps with one branch line as before.

Then, prime it with a nonelectric cap attached to the other detonating cord branch line. When priming the bangalore with a nonelectric cap, use the CTP method. Too many wraps will extend the detonating cord past the booster charge housing, possibly causing the torpedo to be cut without detonating. Too few wraps may cause the torpedo to only be creased, without detonating. Figure , page , shows a single-firing system.

Each charge is single-primed with a branch line. The branch line is tied to the line main or ring main. Tying to the ring main is preferred, but construction of a ring main may not be possible because of the amount of detonating cord. The ring main decreases the chances of a misfire, if a break or cut occurs anywhere within the ring main.

The electric, nonelectric, or combination initiation sets are then taped onto the firing system. When using a combination initiation set, the electric initiation system is always the primary means of initiation. When using dual, nonelectric initiation sets, the shorter time fuse is the primary initiation set Figure , page DUAL Figure , page , shows a dual-firing system.

Each charge is dual-primed with two branch lines Figure , page One branch line is tied to one firing system, and the other branch line is tied to an independent firing system. Line mains or ring mains may be used; however, they should not be mixed. To help prevent misfires, use detonating-cord crossovers. Crossovers are used to tie both firing systems together at the ends.

The initiation sets are taped in with the primary initiation set going to one firing system and the secondary going to the other. Figure , page , shows a dual-firing system using horizontal and vertical ring mains. The complexity of a target or obstacle may necessitate using multiple line mains or ring mains for simultaneous detonation.

These will be referred to as horizontal and vertical lines or ring mains. A firing system uses detonating cord to transmit a shock wave from the initiation set to the explosive charge. Detonating cord is versatile and easy to. Can also be electric-initiated. Figure Single-firing system single-initiated, single-fired, single-primed. Line main Ring main Ring main. Branch lines Branch lines Branch lines.

Initiation points Initiation points. Nonelectric-initiated Combination-initiated Electric-initiated. Single-firing system dual-initiated, single-fired, single-primed. Line main Ring main.

Crossovers Charges Branch lines Charges Crossovers. Electric is always Combination-initiated the primary-initiation set. It is useful for underwater, underground, and above-ground blasting because the blasting cap of the initiation set may remain above water or above gro un d and d oe s no t h a ve to be ins er ted d ire ctly into the c harg e.

Detonating-cord firing systems combined with detonating-cord priming are the safest and most efficient ways to conduct military demolition missions.

Initiate detonating cord with nonelectric or electric initiation sets. Attach the blasting cap, electric or nonelectric, to the detonating cord with tape. You can use string, cloth, or fine wire if tape is not available.

Tape the cap securely to a point 6 inches from the end of the detonating cord to overcome moisture contamination. The tape must not conceal either end of the cap. Taping in this way allows you to inspect the cap in case it misfires. Horizontal ring main Detonating-cord Vertical ring main above detonating cord crossover the deck detonating cord. Charges Charges above deck on deck Buried charges.

Horizontal ring main Initiation points detonating cord Vertical ring main above Detonating-cord crossover the deck detonating cord. Use square knots or detonating-cord clips to splice the ends of detonating cord Figure Always reinforce the splice with tape.

Do not splice detonating cord on branch lines. Square knots may be placed in water or in the ground, but the cord must be detonated from a dry end or above ground. Allow 6-inch tails on square knots to prevent misfires from moisture contamination. Paragraph , page , describes the process for connecting detonating cord with detonating-cord clips. A branch line is a length of detonating cord between the charge and the firing system.

Attach branch lines to a detonating-cord ring or line main to fire multiple charges. Combining the branch line with an initiation set allows you to fire a single branch line. Fasten a branch line to a main line with a detonating-cord clip Figure , page , a girth hitch with an extra turn Figure , page , a cherry knot, or a Gregory knot. The connections of branch lines and ring or line mains should intersect at right angles.

If these connections are not at right angles, the branch line may be blown off the line main without complete detonation. To prevent moisture contamination and ensure positive detonation, leave at least 6 inches of the running end of the branch line beyond the tie. It does not matter which side of the knot the 6-inch tail is on at the connection of the ring or line main. A line main can fire a single charge or multiple charges Figure , page , but if a break in the line occurs, the detonating wave will stop at the break.

When the risk of having a line main cut is unacceptable, use a ring main. Use line mains only when speed is essential. You can connect any number of branch lines to a line main. However, you connect only one branch line at any one point unless you use a British junction Figure , page Ring mains are preferred over line mains because the detonating wave approaches the branch lines from two directions. The charges will detonate even when there is a break in the ring main.

FM 3-34.214 (FM 5-250) EXPLOSIVES AND DEMOLITIONS July

A ring main will detonate an unlimited number of charges. Branch-line connections to the ring main should be at right angles. Kinks in the lines should not be sharp. You can connect any number of branch lines to the ring main; however, never connect a branch line at the point where the ring main is spliced.

When making branch-line connections, avoid crossing lines. If a line crossing is necessary, provide at least 1 foot of clearance between the detonating cords.

Otherwise, the cords may cut each other and may destroy the firing system. Girth hitch with an 90o extra turn 6" Branch line. Method 1 Make a ring main by bringing the detonating cord back in the form of a loop and attaching it to itself with a girth hitch with an extra turn Figure , page , diagram 1.

Method 2 Make a ring main by making a U-shape with the detonating cord, then attaching a detonating-cord crossover at the open end of the U. Use girth hitches with extra turns when attaching the crossover Figure , diagram 2. Girth hitch with an extra turn. All branch lines to charges must be equal in length, either with or without cap.

Initiation Initiation points points. Ring main Branch lines Branch lines Detonating-cord crossover.

Girth hitch with an extra turn Girth hitch with an extra turn Diagram 1 Diagram 2. An advantage of the U-shaped ring main is that it provides two points of attachment for initiation sets. Method 3 Make a ring main by making a U-shape with the detonating cord. Bring the two ends of the U-shape together. Whenever possible, dual initiate a single line or ring main as shown in Figure Place the blasting cap that will detonate first closest to the end of the detonating cord for example, the electric cap of a combination of initiation sets.

Doing this will ensure the integrity of the backup system if the first cap detonates and fails to initiate the line main. Initiate a dual-firing system as shown in Figure , page However, the blasting caps are still connected as shown in Figure , page Primary initiation Secondary initiation system system Line main.

Minimum of 6 inches between caps Minimum of 6 inches between primary cap and end of line main. Place the time fuse so that the fuse will not curl up and prematurely detonate the blasting cap crimped to it. Calculating and Placing Charges Charge calculations are discussed in this chapter. Included in this chapter are the six-step problem-solving formats for all types of calculations and the different methods for placing charges.

The amount and placement of explosives are key factors in military demolition projects. Formulas are available to help an engineer calculate the required amount of explosives. Demolition principles and critical-factor analysis also guide a soldier in working with explosive charges. The available formulas for demolition calculations are based on the detonation effects, the charge-dimension significance, and the charge-placement significance.

When an explosive detonates, it violently changes into highly compressed gas. The explosive type, density, confinement, and dimensions determine the rate at which the charge changes to a gaseous state. The resulting pressure then forms a compressive shock wave that shatters and displaces objects in its path.

Splice the ends of detonating cords by first overlapping them approximately 12 inches. Then secure each loose end to the other cord by using a clip. Finally, bend the tongues of the clips firmly over both strands. Make the connection stronger by bending the trough end of the clip back over the tongue Ml Adhesive Paste.

Ml adhesive paste is a sticky, putty-like substance that is used to attach charges to flat, overhead or vertical surfaces. Adhesive paste is useful for holding charges while tying them in place or, under some conditions, for holding without ties. This paste does not adhere satisfactorily to dirty, dusty, wet, or oily surfaces. Ml adhesive paste becomes useless when softened by water.

Pressure-Sensitive Adhesive Tape. Pressure-sensitive tape is replacing Ml adhesive paste. Pressure sensitive tape has better holding properties and is more easily and quickly applied.

This tape is coated on both sides with pressure-sensitive adhesive and requires no solvent or heat to apply. It is available in 2-inch- wide rolls , 72 yards long. This tape is effective for holding charges to dry, clean wood, steel, or concrete. This tape does not adhere to dirty, wet, oily, or frozen surfaces.

Supplementary Adhesive for Demolition Charges. This adhesive is used to hold demolition charges when the target surface is below freezing, wet, or underwater. Supplementary adhesive b.

Apply the adhesive to the target surface and the file: Waterproof Sealing Compound. This sealant is for waterproofing connections between time blasting fuses or detonating cords and nonelectric blasting caps.

The sealing compound will not make a permanent waterproof seal. Since this sealant is not permanent, fire underwater demolitions as soon as possible after placing them. M2 Cap Crimper. Use the M2 cap crimper for squeezing the shell of a nonelectric blasting cap around a time blasting fuse, standard coupling base, or detonating cord. Crimp the shell securely enough to keep the fuse, base, or cord from being pulled off, but not so tightly that it interferes with the operation of the initiating device.

A stop on the handle helps to limit the amount of crimp applied. The M2 crimper forms a water-resistant groove completely around the blasting cap. Apply a sealing compound to the crimped end of the blasting cap to waterproof it. The rear portion of each jaw is shaped and sharpened for cutting fuses and detonating cords. One leg of the handle is pointed for punching cap wells in file: M2 cap crimper Figure M51 blasting-cap test set FM - 1 explosive materials.

fm_5-250_explosives_and_demolitions.pdf - FM 5-250...

The other leg has a screwdriver end. Cap crimpers are made of a soft, nonsparking metal that conducts electricity. Do not use them as pliers because such use damages the crimping surface.

Ensure crimp hole is round not elongated and the cutting jaws are not jagged. Keep the cutting jaws clean, and use them only for cutting fuses and detonating cords. M51 Blasting-Cap Test Set. The test set is a self-contained unit with a magneto-type impulse generator, an indicator lamp, a handle to activate the generator, and two binding posts for attaching firing leads.

The test set is waterproof and capable of operation at temperatures as low as degrees Fahrenheit b. Check the continuity of firing wire, blasting caps, and firing circuits by connecting the leads to the test-set binding posts and then depressing the handle sharply.

If there is a continuous intact circuit, even one created by a short circuit, the indicator lamp will flash. When the circuit is open, the indicator lamp will not flash. Handle the test set carefully and keep it dry to assure optimum use. Before using, ensure the test set is operating properly by using the following procedure: The indicator lamp should flash. This time the indicator lamp should not flash. Blasting Machines. Blasting machines provide the electric impulse needed to initiate electric blasting-cap operations.

When operated, the M32 and M34 models use an alternator and a capacitor to energize the circuit. M32 Cap Blasting Machine. This small, lightweight blasting machine produces adequate current to initiate 10 electrical caps connected in series using feet of WD-I cable.

To operate the machine, use the following procedure: M32 blasting machine 1 Check the machine for proper operation. Release the blasting machine handle by rotating the retaining ring downward while pushing in on the handle. The handle will automatically spring outward from the body of the machine. The lamp is located between the wire terminal posts and cannot be seen until it flashes, since it is covered by green plastic. Be sure to hold the machine correctly, as the handles are easily broken.

Normally, no more than three or four strokes are required. M34 Cap Blasting Machine. This small, lightweight machine produces adequate current to initiate 50 electrical caps connected in a series.

It looks like the M32 blasting machine Figure except for a black band around the base and a steel-reinforced actuating handle. Test and operate the M34 in the same manner as the M Firing Wire and Reels.

Types of Firing Wire. Wire for firing electric charges is available in and foot coils. The two-conductor AWG Number 18 is a plastic-covered or rubber-covered wire available in foot rolls. This wire is wound on an RL39A reel unit. The single conductor. AWG Number 20 annunciator wire is available in foot coils and is used to make connections between blasting caps and firing wire.

The RL39A reel, with spool, accommodates feet of wire. The reel has a handle assembly, a crank, an axle, and two carrying straps Figure The fixed end of the wire extends from the spool through a hole in the side of the drum and fastens to two brass thumb-out terminals. The carrying handles are two U-shaped steel rods. A loop at each end encircles a bearing assembly to accommodate the axle. The crank is riveted to one end of the axle, and a cotter pin holds the axle in place on the opposite end.

Firing Devices and Other Accessory Equipment a. M60 Weatherproof Fuze Igniter. This device is for igniting timed blasting fuse in all weather conditions, even underwater, if properly waterproofed. Insert the fuse through a rubber sealing grommet and into a split collet. This procedure secures the fuse when the end capon the igniter is tightened. Pulling the pull ring releases the striker assembly, allowing the firing pin to initiate the primer, file: Chapter 2 gives detailed operating instructions for the M60 igniter.

M60 fuze igniter b. Demolition Equipment Set. This set Electric and Nonelectric Explosive Initiating Demolition Equipment Set is an assembly of tools necessary for performing demolition operations. The individual items listed in this set are available separately. Non-electric Initiation Sets. Components Assembly. A non-electric system uses a non-electric blasting cap as the initiator.

The initiation set consists of a fuse igniter produces flame that lights the time fuse , the time blasting fuse transmits the flame that fires the blasting cap , and a non-electric blasting cap provides shock adequate to detonate the explosive Figure When combined with detonating cord, a single initiation set can fire multiple charges. Nonelectric initiation set b. Preparation Sequence. Preparing demolitions for non- electric initiation follows a specified process.

This process file: Checking the time fuse. Step 2. Preparing the time fuse. Step 3. Attaching the fuse igniter. Step 4. Installing the primer adapter. Step 5. Placing the blasting cap 1 Checking Time Fuse. Test every coil of fuse, or remnant of a coil, using the burning-rate test prior to use. One test per day per coil is sufficient. Never use the first and last 6 inches of a coil because moisture may have penetrated the coil to this length.

Using an M2 crimper, cut and discard a 6-inch length from the free end of the fuse Figure Cut off and use a 3-foot length of the fuse to check the burning rate. Ignite the fuse and note the time it takes for the fuse to burn.

Compute the burning rate per foot by dividing the bum time in seconds by the length in feet. Cut the fuse long enough to allow the person detonating the charge to reach safety walking at a normal pace before the explosion.

Walk and time this distance prior to cutting the fuse to length. Do not cut the fuse too far in advance, since the fuse may absorb moisture into the open ends. Do not allow the time fuse to bend sharply, as you may crack the black powder core, resulting in a file: To attach an M60 weatherproof fuze igniter, unscrew the fuse holder cap two or three turns, but do not remove the cap.

Press the shipping plug into the igniter to release the split collet Figure , page Rotate and remove the plug from the igniter. Insert the free end of the time fuse as far as possible into the space left by the removed shipping plug.

Sufficiently tighten the holder cap to hold the fuse and weatherproof the joint. If you use a priming adapter to hold a non-electric blasting cap, place the time fuse through the adapter before installing crimping the blasting cap onto the fuse.

Ensure the adapter threads are pointing to the end of the time fuse that will receive the blasting cap. Hold the cap between the thumb and ring finger of one hand, with the forefinger of the same hand on the closed end of the blasting cap.

Inspect the blasting cap by looking into the open end. You should see a yellow- colored ignition charge. If dirt or any foreign matter is present, do the following: Aim the open end of the cap at the palm of the second hand. If the foreign matter does not dislodge, do not use the cap.

Use this procedure for installing blasting caps onto fuse. Using this procedure will allow accurate crimping, even in darkness, because finger placement guides the crimpers to the open end of the blasting cap. Use the following procedures to attach a non- electric blasting cap onto time fuse: Hold the time blasting fuse vertically with the square-cut end up, and slip the blasting cap gently down over the fuse so the flash charge in the cap touches the fuse.

Never force a time fuse into a blasting cap, for example, by twisting or any other method. If the fuse end is flat or too large to enter the blasting cap freely, roll the fuse between the thumb and fingers until it will freely enter the cap.

A rough, jagged-cut fuse inserted in a blasting cap can cause a misfire. If the cutting jaws of the M2 crimper are unserviceable, use a sharp knife to cut the fuse. When using a knife to cut fuse squarely, cut the fuse against a solid, non-sparking surface such as wood. While applying slight pressure with the forefinger on the file: Using the opposite hand, grasp the crimpers. The thumb and ring finger that hold the fuse will be below the crimpers.

Rest the second finger of the hand holding the fuse on top of the crimpers to prevent the crimpers from sliding up the cap.

Crimping a blasting cap onto fuse Extend both arms straight out while rotating the hands so that the closed end of the blasting cap is pointing away from the body and from other personnel. Crimp the blasting cap by firmly squeezing the M2 crimper handles together, maintaining eye contact with the blasting cap. Inspect the crimp after you have finished. Ensure that the fuse and cap are properly joined by gently trying to pull them apart file: Attach the M60 fuze igniter to the time fuse before crimping a blasting cap to the opposite end.

Do not remove the safety pin until you are ready to detonate the charge. Point the cap out and away from the body during crimping. If the cap is to remain in place several days before firing, protect the joint between the cap and the timed blasting fuse with a coat of sealing compound or similar substance.

This sealing compound will not make a waterproof seal; therefore, fire submerged charges immediately. See paragraph page for procedures on handling non-electric misfires. Fuse Initiation. To fire the assembly, hold the M60 igniter in one hand and remove the safety pin with the other. Grasp the pull ring and give it a quick, hard pull. In the event of a misfire, reset the M60 by pushing the plunger all the way in, rotate it left and right, and attempt to fire as before.

If a fuze igniter is not available, light the time blasting fuse with a match. Split the fuse at the end Figure and place the head of an unlit match in the powder train. Light the inserted match head with a flaming match, or rub the abrasive on the match box against it. It may be necessary to use two match heads during windy conditions.

Lighting time fuse with a match Electric Initiation Sets. Use the process below to make an electric initiation set. This process includes — Testing and maintaining control of the blasting machine. Testing the firing wire on the reel, shunted and unshunted. Laying out the firing wire completely off the reel. Retesting the firing wire, shunted and unshunted. Testing the blasting caps.

Connecting the series circuit. Connecting the firing wire. Testing the entire circuit. Priming the charges. An electric system uses an electric blasting cap as the explosion initiator.

The initiation set consists of an electric blasting cap, the firing wire, and a blasting machine Figure An electric impulse usually provided by a blasting machine travels through the firing wires and blasting cap leads, detonating the blasting cap which initiates the explosion. Radio waves can also detonate electric blasting caps.

Therefore, observe the minimum safe distances listed in Chapter 6 page at all times. TM provides detailed information about electric blasting equipment. Electric initiation set Always follow the procedure below when preparing an electric initiation set: The supervisor is responsible for controlling all blasting machines.

Squeeze-tie test-set handle. The indicator lamp should NOT flash. If it does, the lamp's flash indicates a short circuit in the firing wire Figure Testing firing wire on the reel b Shunt the wires atone end and connect the leads from the other end to the posts of the M51 test set.

Squeeze the test-set handle. If it does not, the lamp's failure to light indicates a break in the firing wire Figure Use at least three degree turns to shunt wires. More than one reel of wire may be necessary. Always bury firing wire or lay it flat on the ground. Avoid creating any loops in the wire lay it in as straight a line as possible.

Cut the wire to length. Do not connect it to a blasting machine through the unused portion of wire on the reel. The process of unreeling the wire may have separated broken wires not found when the wire was tested on the reel. Do this to ensure that no one tampers with the wires or fires the charges prematurely. Hand signals are necessary because of the distance involved between the charges and the firing position.

The man testing the wire also can give these signals directly to the soldier at the opposite end of the wire or, if they cannot see each other, through intermediate positions or over the radio. The tester indicates to his assistant that he wants the far end of the firing wire unshunted by extending both arms straight out at shoulder height. When the tester wants the far end of the firing wire shunted, he signals to his assistant by clasping his hands together and extending his arms over his head, elbows bent, forming a diamond shape.

After shunting the firing wire, the assistant repeats the signal, indicating to the tester that his wire is shunted. Place the cap in the palm of your hand, lead wires passing between your thumb and index finger.

Doing this prevents tension on the wires in the cap and prevents the cap from being dropped. Completely unreel the cap wires from the cardboard spool. Avoid allowing the wires to slip offends of the cardboard spool, since this will cause excessive twists and kinks in the wires and prevent the wires from separating properly. Keep your back to the blasting cap when testing it. Hold or attach the second lead wire to the other binding post and squeeze the test-set handle.

The blasting cap is good if the indicator lamp flashes. If the lamp does not flash, the cap is defective; do not use it. When two or more blasting caps are required for a demolition operation, you may use one of the series circuits illustrated in Figure Diagram 1 Diagram 2 Figure Series circuit Use the following procedure: Protect all joints in the circuit with electrical insulation tape.

Do not use the cardboard spool that comes with the blasting cap to insulate these connections. After the series is completed, connect the two free blasting cap wires to the M51 test set. The indicator lamp should flash to indicate a good circuit.

If the lamp does not flash, check your connections and blasting caps again. Never use the cardboard spool that comes with the blasting cap to insulate this connection. The firing wire is likely to break when bent to fit into the spool.

Before priming the charges or connecting blasting caps to ring mains, test the circuit from the firing point. Use the following procedure: Squeeze the firing handle. The indicator lamp should flash, indicating a proper circuit. WARNING Do not prime charges or connect electric blasting caps to detonating cord until all other steps of the preparation sequence have been completed.

Prime the charges and return to the firing point. This is the last step prior to actually returning to the firing point and firing the circuit. Circuit Initiation. At this point the initiation set is complete. Do not connect the blasting machine until all personnel are accounted for and the charge is ready to fire.

When all personnel are clear, install the blasting machine file: Chapter 6 page covers procedures for electric misfires.

Splicing Electric Wires. Strip the insulating material from the end of insulated wires before splicing. Remove approximately 1 Vfe inches of insulation from the end of each wire Figure , diagram 1. Also remove any coating on the wire, such as enamel, by carefully scraping the wire with the back of a knife blade or other suitable tool. Do not nick, cut, or weaken the bare wire. Twist multiple-strand wires lightly after scraping. Use the Western Union pigtail splice Figure 2- 8, page to splice two wires.

Splice two pairs of wires in the same way as the two-wire splice Figure A short circuit may occur at a splice if you do not practice some caution. For example, when you splice pairs of wires, stagger the splices and place a tie between them Figure , diagram 1. Another method of preventing a short circuit in a splice is using the alternate method Figure , diagram 2.

In the alternate method, separate the splices rather than stagger them. Insulate the splices from the ground or other conductors by wrapping them with friction tape or other electric insulating tape. Always insulate splices. Diagram 2 Figure Two-wire splice e. Series Circuits. Use this circuit to connect two or more electric blasting caps to a single blasting machine Figure 2- 7, diagram 1 , page Prepare a common series circuit by connecting one blasting cap to another until only two end wires are free.

Shunt the two end wires until you are ready to proceed with the next step. Connect the free ends of the cap lead wires to the ends of the firing wire. Use connecting wires usually annunciator wire when the distance between blasting caps is greater than the length of the usual cap lead wires.

The leapfrog method of connecting caps in a series is useful for firing any long line of charges Figure 2- 7, diagram 2, page This method is performed by starting at one end of a row of charges and priming alternate charges to the opposite end and then priming the remaining charges on the return leg of the series. This method eliminates the necessity for a long return lead from the far end of the line of charges. Appendix E has additional information on series circuits.

There is seldom a need for this type of circuit, since detonating cord, when combined with a single blasting cap, will fire multiple charges. Priming Systems The three methods of priming charges are non-electric, electric, and detonating-cord.

FM 5-250 Explosives & Demolitions

Non-electric and electric priming involves directly inserting file: Use the direct-insertion method only when employing shaped charges. Detonating- cord priming is the preferred method for priming all other charges since it involves fewer blasting caps, makes priming and misfire investigation safer, and allows charges to be primed at State of Readiness 1 safe when in place on a reserved demolition. You can crimp non-electric blasting caps to detonating cord as well as time fuse.

This capability permits simultaneous firing of multiple charges primed with a blasting cap. TNT blocks have threaded cap wells. Use priming adapters, if available, to secure non-electric blasting caps and timed blasting fuses to TNT blocks with threaded cap wells Figure When priming adapters are not available, prime TNT blocks with threaded cap wells as follows: Nonelectric priming with adapter file: Adhesive tape can also effectively secure blasting caps in charges. Do not tie siring so tightly that the powder train is broken In the fuse.

Electrical or friction tape may be substituted for string if necessary. Use the following procedure for priming TNT block, using the priming adapter: Ensure the blasting cap protrudes from the threaded end of the adapter. Electric priming with adapter c Insert the blasting cap into the threaded cap well of the TNT block and screw the adapter into place.

If a priming adapter is not available, use the following procedure: Tie the lead wires around the block, using two half hitches or a girth hitch Figure 2- Allow some slack in the wires between the blasting cap and the tie to prevent any tension on the blasting-cap lead wires.

Electric priming without adapter file: Use the following methods to prime TNT blocks with detonating cord: A 6-inch length of detonating cord equals the power output of a blasting cap. However, detonating cord will not detonate explosives as reliably as a blasting cap because its power is not as concentrated.

Therefore, always use several turns or a knot of detonating cord for priming charges. Lay one end l-foot length of detonating cord at an angle across the explosive.

Then, wrap the running end around the block three turns, laying the wraps over the standing end. On the fourth wrap, slip the running end under all wraps, parallel to the standing end and draw the wraps tight.

Doing this forms a clove hitch with two extra turns. Mathod 2 Figure Priming TNT with detonating cord file: Tie the detonating cord around the explosive block with a clove hitch and two extra turns. Fit the cord snugly against the block, and push the loops close together. Place a loop of detonating cordon the explosive, leaving sufficient length on the end to make four turns around the block and loop with the remaining end of the detonating cord. When starting the first wrap, ensure that you immediately cross over the standing end of the loop, working your way to the closed end of the loop.

Pass the free end of the detonating cord through the loop and pull it tight. This forms a knot around the outside of the block. Priming M C4 Demolition Blocks.

Non-electric and Electric. C4 blocks do not have a cap well; therefore, you will have to make one. If the blasting cap does not fit the hole or cut, do not force the cap, make the hole larger. To prime plastic explosive with detonating cord, use the following procedure: Priming plastic explosives with detonating cord 2 Cut a notch out of the explosive, large enough to insert the knot you formed.

Ensure there is at least Vz inch of explosive on all sides of the knot. It is not recommended that plastic explosives be primed by wrapping them with detonating cord, since insufficient wraps will not properly detonate the explosive charge.

Priming M and M Demolition Charges. Use one of the following methods to prime M1 18 and M demolition charges: Attach an M8 blasting cap holder to the end or side of the sheet explosive. Insert an electric or a non-electric blasting cap into the holder until the end of the cap presses against the sheet explosive. The M8 blasting cap holder has three slanted, protruding teeth which prevent the clip from withdrawing from the explosive.

Two dimpled spring arms firmly hold the blasting cap in the M8 holder. Priming sheet explosives 2 Method 2 Figure , page Insert the blasting cap to the limit of the notch. Secure the blasting cap with a strip of sheet explosive. Insert the end of the blasting cap 1 V2 inches between two sheets of explosive. Sheet explosives also can be primed file: Insert the knot between two sheets of explosive or place the knot on top of the sheet explosive and secure it with a small strip of sheet explosive.

The knot must be covered on all sides with at least V2 inch of explosive. Priming Dynamite. Prime dynamite at either end or side. Choose the method that will prevent damage to the primer during placement. There are three methods for priming dynamite non-electrically: End-Prlmlng Method Figure Nonelectric end priming of dynamite 3 Side-Priming Method Figure , page Slightly slant the cap well so the blasting cap, when inserted, will be nearly parallel to the side of the cartridge and the explosive end of the cap will be at a point nearest the middle of the cartridge.

Then, wrap the string tightly around the cartridge, making two or three turns before tying it. Cover the string with a weatherproof sealing compound. Nonelectric side priming of dynamite b. Use the following method for priming with electric blasting caps: You also can use detonating cord to prime dynamite.

Using the M2 crimpers, start approximately 1 inch from either end of the dynamite charge and punch four equally spaced holes through the dynamite cartridge Figure Make sure to rotate the cartridge degrees after punching each hole to keep the holes parallel.

Lace detonating cord through the holes in the same direction the holes were punched. Take care not to file: Secure the detonating cord tail by passing it between the detonating cord lace and the dynamite charge. Electric priming of dynamite Because the cratering charge is primarily an underground charge, prime it only with detonating cord. Use dual priming to protect against misfires Figure , diagram 2, page Tie an overhand knot, with a 6-inch overhang, at one end of the length of detonating cord.

Pass the opposite end of the detonating cord up through the detonating cord tunnel Figure , diagram 1 of the cratering charge.

When wet, ammonium nitrate is ineffective. Do not use damaged or rusty charges. When dual priming a single pound cratering charge, use a minimum of one pound of explosive. Prime a block of TNT or package of C4 with detonating cord paragraphs c, page , and b, page , respectively and tape this charge to the center of the cratering charge Figure , diagram 2.

The detonating file: Twelve-foot branch lines should be adequate. When placing two cratering charges in the same borehole, prime only the detonating cord tunnels of each charge. In this manner, the borehole is dual-primed and extra explosives are not required, as shown in Figure , diagram 3.

However, the charge may be placed anywhere along the center. Priming ammonium-nitrate cratering charge The M2A4 and M3A1 are primed only with electric or non-electric blasting caps.

These charges have a threaded cap well at the top of the cone. Prime them with a blasting cap as shown in Figure Use a piece of string, cloth, or tape to hold the cap if a file: Simultaneously detonate multiple shaped charges to create a line of boreholes for cratering charges by connecting each charge into a detonating-cord ring or line main.

Use the following procedure for priming shaped charges: Crimp a non-electric blasting cap to a branch line. Connect the branch line to the ring main. Insert the blasting cap into the blasting cap well of the shaped charge. When detonating multiple shaped charges, make all branch-line connections before priming any shaped charges. Prime them only with a blasting cap in the blasting cap well. Priming shaped charges Priming the Bangalore Torpedo. Insert the blasting cap of a non-electric initiation set directly into the cap well of a torpedo section.

If a priming adapter is not available, use tape or string to hold the blasting cap in place Figure , diagram 1 , page 2- Priming a Bangalore torpedo with a blasting cap b. Insert the blasting cap of an electric initiation set into the cap well of a torpedo section. If a priming adapter is not available, hold the cap in place by taping or tying with two half hitches the lead wires to the end of the torpedo. Allow some slack in the wires between the blasting cap and the tie to prevent tension on the blasting cap leads.

Prime the torpedo by wrapping detonating cord eight times around the end of the section, just below the bevel Figure After pulling the knot tight, insert the short end of the detonating cord into the cap well and secure it with tape.

Never use the short end tail of the detonating cord to initiate the torpedo. Initiation must come from the running end of the detonating cord. Too many wraps will extend the detonating cord past the booster charge housing, possibly causing the torpedo to be cut without detonating.

Too few wraps may cause the torpedo to only be crimped, without detonating. Firing Systems 1. Types of Firing Systems. There are two types of firing systems: Chapter 5 covers the tactical applications for these systems. Single-firing system single-initiated, single-fired, single-primed a. Figure shows a single-firing system Each charge is singly primed with a branch line. The branch line is tied to the line main or ring main. Tying to the ring main is preferred but construction of a ring main may not be possible because of the amount of detonating cord.

The ring main decreases the chances of a misfire should a break or cut occur anywhere within the ring main. The electric, non-electric, or combination initiation systems are then taped onto the firing system. When using a combination initiation system, the electric initiation system is always the primary means of initiation. When using dual, non-electric initiation systems, the shorter time fuse is the primary initiation system Figure Single-firing system dual-initiated, singled-fired, single-primed b.

Figure page shows a dual-firing system. Each charge is dual-primed with two branch lines Figure , page One branch line is tied to one firing system, and the other branch line is tied to an independent firing system.

Line mains or ring mains may be used; however, they should not be mixed. To help prevent misfires, use detonating-cord crossovers. Crossovers are used to tie both firing systems together at the ends. The initiation systems are taped in the primary initiation system goes to one firing system, the secondary goes to the other.

Dual-firing system dual-installed, dual-fired, dual-primed Figure Dual-primed charge Figure shows a dual-firing system using horizontal and vertical ring mains. The complexity simultaneous detonation. These will be referred to as horizontal and vertical lines or ring mains. Dual-firing system using a bridge as a possible target of a target or obstacle may necessitate using multiple line mains or ring mains for A firing system uses detonating cord to transmit a shock wave from the initiation set to the explosive charge.

Detonating cord is versatile and easy to install. It is useful for underwater, underground, and above-ground blasting because the blasting cap of the initiation set may remain above water or above ground and does not have to be inserted directly into the charge.

Detonating-cord firing systems combined with detonating-cord priming are the safest and most efficient ways to conduct military demolition missions. Initiate detonating cord only with non-electric or electric initiation sets. Attaching the Blasting Cap. Attach the blasting cap, electric or non-electric, to the detonating cord with tape. You can use string, cloth, or fine wire if tape is not available.

Tape the cap securely to a point 6 inches from the end of the detonating cord to overcome moisture file: The tape must not conceal either end of the cap. Taping in this way allows you to inspect the cap in case it misfires. Attaching blasting cap to detonating cord Detonating-Cord Connections.

Use square knots or detonating-cord clips to splice the ends of detonating cord Figure Square knots may be placed in water or in the ground, but the cord must be detonated from a dry end or above ground. Allow 6-inch tails on square knots to prevent misfires from moisture contamination.

Paragraph 1- 21 page describes the process for connecting detonating cord with detonating-cord clips. Line main detonating cord Time fuse FM a. Branch Line. A branch line is nothing more than a length of detonating cord. Attach branch lines to a detonating-cord ring or line main to fire multiple charges. Combining the branch line with an initiation set allows you to fire a single branch line.

If possible, branch lines should not be longer than 12 feet from the charge to the ring or line main. A longer branch line is too susceptible to damage that may isolate the charge. Fasten a branch line to a main line with a detonating-cord clip Figure 1 -1 8, page 1 -1 7 or a girth hitch with an extra turn Figure The connections of branch lines and ring or line mains should intersect at right degree angles. If these connections are not at right angles, the branch line may be blown off the line main without complete detonation.

To prevent moisture contamination and ensure positive detonation, leave at least 6 inches of the running end of the branch line beyond the tie. It does not matter which side of the knot your 6-inch overhang is on at the connection of the ring or line main. Girth hitch with an extra turn b. Ring Main. Ring mains are preferred over line mains because the detonating wave approaches the branch lines from two directions.

The charges will detonate even when them is a break in the ring main. A ring main will detonate an almost unlimited number of charges. Branch-line connections at the ring main should be at right angles. Kinks in the lines should not be sharp.

You can connect any number of branch lines to the ring main; however, never connect a branch line at the point where the ring main is spliced. When making branch-line connections, avoid crossing lines. If a line crossing is necessary, provide at least 1 foot of clearance between the detonating cords. Otherwise, the cords will cut each other and destroy the firing system.

Make a ring main by bringing the line main back in the form of a loop and attaching it to itself with a girth hitch with an extra turn Figure , diagram 1. Make a ring main by making a U-shape with file: Use girth hitches with extra turns when attaching the crossover Figure , diagram 2.

An advantage of the U-shaped ring main is that it provides two points of attachment for initiation sets. Ring mains c. Line Main. A line main will fire multiple charges Figure 2- 34 , but if a break in the line occurs, the detonating wave will stop at the break.

When the risk of having a line main cut is unacceptable, use a ring main. Use line mains only when speed is essential and a risk of failure is acceptable. You can connect any number of branch lines to a line main. However, connect only one branch line at any one point unless you use a junction box Figure , page Line main with branch lines Initiating Lines and Mains. Line Main and Branch Line. Whenever possible, dual initiate a line main or a branch line Figure , page 2- Place the blasting cap that will detonate first closest to the end of the detonating cord for example, the electric cap of a combination of initiation sets.

Doing this will ensure the integrity of the backup system when the first cap detonates and fails to initiate the line main. Do not try to get both caps to detonate at the same time. This is virtually impossible to do with time fuse. Stagger the detonations a minimum of 10 seconds. Initiate ring mains as shown in Figures The blasting caps are still connected as shown in Figure 2- 36 page , but by having one on each side of the ring main, the chances of both caps becoming isolated from the ring are greatly reduced.

Demolition The amount and placement of explosives are key factors in military demolition projects. Formulas are available to help the engineer calculate the required amount of explosives.

Demolition principles and critical-factor analysis also guide the soldier in working with explosive charges. The available formulas for demolition calculations are based on the following factors: Effects of Detonation. When an explosive detonates, it violently changes into highly compressed gas. The explosive type, density, confinement, and dimensions determine the rate at which the charge changes to a gaseous state.

The resulting pressure then forms a compressive shock wave that shatters and displaces objects in its path. A high-explosive charge detonated in direct contact with a solid object produces three detectable destructive affects: The charge's shock wave deforms the surface of the object directly under the charge. When the charge is placed on a concrete surface, it causes a compressive shock wave that crumbles the concrete in the immediate vicinity of the charge, forming a crater.

When file: The charge's shock wave chips away at the surface of the object directly under the charge. This action is known as spalling. If the charge is large enough, it will span the opposite side of the object. Because of the difference in density between the target and the air, the charge's compressive shock wave reflects as a tensile shock wave from the free surface, if the target has a free surface on the side opposite the charge.

This action causes spalling of the target-free surface. The crater and spans may meet to forma hole through the wall in concrete demolitions. On a steel plate, the charge may create one span in the shape of the explosive charge, throwing the spall from the plate. If the charge is large enough, the expanding gases can create a pressure load on the object that will cause cracking and therefore displace the material.

This effect is known as radial cracking. When placed on concrete walls, the charge may crack the surface into a large number of chunks and project them away from the center of the explosion. When placed on steel plates, the charge may bend the steel away from the center of the explosion.

Significance of Charge Dimensions. The force of an file: The destructive effect depends on the direction in which the explosive force is directed. To transmit the greatest shock, the charge must have the optimal relationship of contact area and thickness to target volume and density. If you spread a calculated charge too thinly, you will not have provided enough space for the shock wave to reach full velocity before striking the target.

In improperly configured explosives too thin or wrong strength , the shock wave tends to travel in a parallel rather than a perpendicular direction to the surface. As a result, the volume of the target will be too much for the resulting Shockwave. Additionally, a thick charge with too small a contact area will transmit a shock wave over too small a target area, with much lateral loss of energy. Significance of Charge Placement.

The destructive effect of an explosive charge also depends on the location of the charge in relation to the target size, shape, and configuration. For the most destructive effect, detonate an explosive of the proper size and shape for the size, shape, and configuration of the target. Any significant air or water gap between the target and explosive will lessen the force of the shock wave. Cut explosives such as sheet or plastic explosives to fit odd-shaped targets.

Whenever possible, place explosive charges to act through the smallest part of the target. Use internal charges to achieve maximum destruction with minimum explosives expense. Tamping external charges increases their destructive file: Types of Charges.

Internal Charges. Place internal charges in boreholes in the target.

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